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pete-9.c is the last of nine entries an anonymous "Pete" submitted to Bignum Bakeoff.[1] It only slightly differs from its predecessor pete-8.c which was a failed attempt at improving upon Pete's largest entry, pete-7.c. Both pete-9.c and pete-8.c produce a much smaller number than pete-7.c because the f(n) function Pete defines in these programs has a bug which causes it to merely square a previously defined number. The only difference between the output of pete-9.c and pete-8.c is that pete-9.c uses 99 at one point instead of 999.

The output of pete-9.c can be precisely expressed as $$z^{16\cdot17^6}(99)$$, where $$z(n) = 9\cdot 2^n$$.

## Approximations in other notations

Notation Approximation
Up-arrow notation $$2 \uparrow\uparrow 386,201,107$$
Hyper-E notation $$E1\#386,201,107$$
Chained arrow notation $$2 \rightarrow 386,201,107 \rightarrow 2$$
Hyperfactorial array notation $$386,201,107!1$$
Fast-growing hierarchy $$f_3(386,201,107)$$
Hardy hierarchy $$H_{\omega^3}(386,201,107)$$
Slow-growing hierarchy $$g_{\varepsilon_0}(386,201,107)$$

## Code

#define Z (9<<(9<<
#define Y Z Z Z Z Z Z Z Z
#define W ))))))))))))))))

#define Q Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
#define O W W W W W W W W W W W W W W W W W

#define P Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q
#define M O O O O O O O O O O O O O O O O O

#define L P P P P P P P P P P P P P P P P P
#define K M M M M M M M M M M M M M M M M M

#define H L L L L L L L L L L L L L L L L L
#define J K K K K K K K K K K K K K K K K K

#define A H H H H H H H H H H H H H H H H H
#define D J J J J J J J J J J J J J J J J J

#define X A A A A A A A A A A A A A A A A A 99\
D D D D D D D D D D D D D D D D D

int B = X;

f(int* a)
{
int C = B, b[X], n = X;

while(n--)
b[n] = a[n];
if(b[n = X - 1]--)
while(C--)
B = f(b);
while(n && !(b[n] = B, b[--n]--))
;
return n ? f(b) : B * B;
}

main()
{
int a[X] = {X};

return f(a);
}


## See also

Large numbers in computers
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