User blog comment:Googleaarex/Okojo-ermine number/@comment-24251128-20140108100449

Indeed f(n) is based on triangle(10^^n), but is not triangle(10^^n). Triangle(10^^n) can be approximated to 10^^(n+1), but precicely defferent from  10^^(n+1). f(n) denotes the differece between each other. For example, (10^10^10^10^10)^(10^10^10^10^10) = 10^10^10^10^10^10.000...000xxx... =  10^10^10^10^10^10^1.000...000xxx... =  10^10^10^10^10^10^10^0.000...000xxx... ,and here this  0.000...000xxx... is f(5). This is quite small.