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'''Pentation''' or '''quintation''' refers to the function \(a \uparrow\uparrow\uparrow b\), where [[Arrow Notation]] is used. It produces numbers very much larger than those produced by [[tetration]].<ref>{{cite web|first=Jonathan|last=Bowers|authorlink=Jonathan Bowers|url=http://www.polytope.net/hedrondude/array.htm|title=Exploding Array Function|accessdate=2013-06-11}}</ref>
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'''Pentation''' or '''quintation''' refers to the function \(a \uparrow\uparrow\uparrow b\), where [[arrow notation]] is used. It produces numbers very much larger than those produced by [[tetration]].<ref>{{cite web|first=Jonathan|last=Bowers|authorlink=Jonathan Bowers|url=http://www.polytope.net/hedrondude/array.htm|title=Exploding Array Function|accessdate=2013-06-11}}</ref>
   
 
Pentation can be written in [[array notation]] as {a,b,3}, in [[chained arrow notation]] as \(a \rightarrow b \rightarrow 3\) and in [[Hyper-E notation]] as E(a)1#1#b.
 
Pentation can be written in [[array notation]] as {a,b,3}, in [[chained arrow notation]] as \(a \rightarrow b \rightarrow 3\) and in [[Hyper-E notation]] as E(a)1#1#b.
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Pentation is less known than its tetrational cousin, but there are a few [[googologism]]s employing it: 3 pentated to 3 is known as [[tritri]], and 10 pentated to 100 is [[gaggol]].
 
Pentation is less known than its tetrational cousin, but there are a few [[googologism]]s employing it: 3 pentated to 3 is known as [[tritri]], and 10 pentated to 100 is [[gaggol]].
   
Sunir Shah uses the notation \(a * b\) to indicate this function.<ref>{{cite web|url=http://c2.com/cgi/wiki?ReallyBigNumbers|title=Really Big Numbers|accessdate=2013-06-11}}</ref> [[Jonathan Bowers]] calls it "a to the b'th tower".<ref>{{cite web|first=Jonathan|last=Bowers|authorlink=Jonathan Bowers|url=http://www.polytope.net/hedrondude/trientrical.htm|title=Array Notation up to Three Entries|accessdate=2013-06-11}}</ref> [[Sbiis Saibian]] proposes \(_{b \leftarrow}a\) in analogy to \({^{b}a}\) for tetration, though he usually uses up-arrows.<ref>{{cite web|first=Sbiis|last=Saibian|authorlink=Sbiis Saibian|url=https://sites.google.com/site/largenumbers/home/3-2/knuth|title=3.2.5 - Ascending With Up Arrows|accessdate=2013-06-11}}</ref>
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Sunir Shah uses the notation \(a * b\) to indicate this function.<ref>{{cite web|url=http://c2.com/cgi/wiki?ReallyBigNumbers|title=Really Big Numbers|accessdate=2013-06-11}}</ref> [[Jonathan Bowers]] calls it "a to the b'th tower".<ref>{{cite web|first=Jonathan|last=Bowers|authorlink=Jonathan Bowers|url=http://www.polytope.net/hedrondude/trientrical.htm|title=Array Notation up to Three Entries|accessdate=2013-06-11}}</ref> [[Sbiis Saibian]] proposes \(_{b \leftarrow}a\) in analogy to \({^{b}a}\) for tetration, though he usually uses up-arrows.<ref>{{cite web|first=Sbiis|last=Saibian|authorlink=Sbiis Saibian|url=https://sites.google.com/site/largenumbers/home/3-2/knuth|title=3.2.3 - Ascending With Up Arrows|accessdate=2015-03-26}}</ref>
   
 
Pentational growth rate is equivalent to \(f_4(n)\) in the [[fast-growing hierarchy]].
 
Pentational growth rate is equivalent to \(f_4(n)\) in the [[fast-growing hierarchy]].
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Tim Urban calls pentation a "power tower feeding frenzy".<ref>[http://waitbutwhy.com/2014/11/1000000-grahams-number.html From 1,000,000 to Graham’s Number]. ''Wait But Why''.</ref>
 
Tim Urban calls pentation a "power tower feeding frenzy".<ref>[http://waitbutwhy.com/2014/11/1000000-grahams-number.html From 1,000,000 to Graham’s Number]. ''Wait But Why''.</ref>
   
===Examples===
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== Examples ==
 
Here are some small examples of pentation in action:
 
Here are some small examples of pentation in action:
   
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*\(5 \uparrow\uparrow\uparrow 5 = {^{^{^{^{5}5}5}5}5}\)
 
*\(5 \uparrow\uparrow\uparrow 5 = {^{^{^{^{5}5}5}5}5}\)
   
=== Pseudocode ===
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== Pseudocode ==
 
Below is an example of pseudocode for pentation.
 
Below is an example of pseudocode for pentation.
   
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'''return''' ''result''
 
'''return''' ''result''
   
=== Sources ===
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== Sources ==
 
<references />
 
<references />
   
=== External Links ===
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== See also ==
 
{{ExtendedOps}}
[http://unionofbranchconfederacies.wikia.com/wiki/Pentation Pentation Wiki]
 
   
 
[[ja:ペンテーション]]
 
[[ja:ペンテーション]]
 
=== See also ===
 
{{ExtendedOps}}
 
 
[[Category:Functions]]
 
[[Category:Functions]]
 
[[Category:Binary operators]]
 
[[Category:Binary operators]]

Revision as of 01:16, 27 March 2015

Pentation or quintation refers to the function \(a \uparrow\uparrow\uparrow b\), where arrow notation is used. It produces numbers very much larger than those produced by tetration.[1]

Pentation can be written in array notation as {a,b,3}, in chained arrow notation as \(a \rightarrow b \rightarrow 3\) and in Hyper-E notation as E(a)1#1#b.

Pentation is less known than its tetrational cousin, but there are a few googologisms employing it: 3 pentated to 3 is known as tritri, and 10 pentated to 100 is gaggol.

Sunir Shah uses the notation \(a * b\) to indicate this function.[2] Jonathan Bowers calls it "a to the b'th tower".[3] Sbiis Saibian proposes \(_{b \leftarrow}a\) in analogy to \({^{b}a}\) for tetration, though he usually uses up-arrows.[4]

Pentational growth rate is equivalent to \(f_4(n)\) in the fast-growing hierarchy.

A strip from the webcomic Saturday Morning Breakfast Cereal suggested the name "penetration" in humorous analogy with sexation.[5]

Tim Urban calls pentation a "power tower feeding frenzy".[6]

Examples

Here are some small examples of pentation in action:

  • \(1 \uparrow\uparrow\uparrow b = 1\)
  • \(a \uparrow\uparrow\uparrow 1 = a\)
  • \(2 \uparrow\uparrow\uparrow 2 = 4\)
  • \(2 \uparrow\uparrow\uparrow 3 = {^{^{2}2}2} = {^{4}2} = 2^{2^{2^{2}}} = 65,536\)
  • \(3 \uparrow\uparrow\uparrow 2 = {^{3}3} = 3^{3^{3}} =\) \(7,625,597,484,987\)

Here are some larger examples:

  • \(3 \uparrow\uparrow\uparrow 3 = {^{^{3}3}3} = {^{7,625,597,484,987}3}\) = tritri, a power tower of 7,625,597,484,987 threes
  • \(5 \uparrow\uparrow\uparrow 2 = {^{5}5} = 5^{5^{5^{5^5}}}\)
  • \(6 \uparrow\uparrow\uparrow 3 = {^{^{6}6}6}\)
  • \(5 \uparrow\uparrow\uparrow 5 = {^{^{^{^{5}5}5}5}5}\)

Pseudocode

Below is an example of pseudocode for pentation.

function pentation(a, b):
    result := 1
    repeat b times:
        result := a tetrated to result
    return result

Sources

See also