This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A258848 #5 Jun 19 2015 15:49:11 %S A258848 8,12,20,32,80,208,512,2304,12288,81920,622592,4931584,38944768, %T A258848 278380544,2122727424,17483677696,128412352512,1348723408896, %U A258848 14768867966976,188484960780288,2416519442792448,30543291749302272,375877192068366336,6101345960934506496 %N A258848 The n-th pi-based arithmetic derivative of 2^3. %F A258848 a(n) = A258851^n(2^3). %p A258848 with(numtheory): %p A258848 d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]): %p A258848 a:= proc(n) option remember; `if`(n=0, 2^3, d(a(n-1))) end: %p A258848 seq(a(n), n=0..23); %Y A258848 Row n=8 of A258850. %Y A258848 Cf. A000720, A258851, A259169. %K A258848 nonn %O A258848 0,1 %A A258848 _Alois P. Heinz_, Jun 12 2015