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 A258855 #4 Jun 12 2015 20:44:48 %S A258855 0,0,0,0,4,0,4,4,208,208,1,0,512,4,20,32,2304,4,32,80,2304,16,53,80, %T A258855 1188,80,32,3888,2432,2,208,1,12288,80,2,4,916,208,7,2432,916,4,30,12, %U A258855 9536,476,4,20,32512,424,32,116,4104,512,20736,156,764,80,332,4 %N A258855 Fifth pi-based arithmetic derivative of n. %H A258855 Alois P. Heinz, <a href="/A258855/b258855.txt">Table of n, a(n) for n = 0..10000</a> %F A258855 a(n) = A258851^5(n). %p A258855 with(numtheory): %p A258855 d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]): %p A258855 A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end: %p A258855 a:= n-> A(n, 5): %p A258855 seq(a(n), n=0..100); %Y A258855 Column k=5 of A258850. %Y A258855 Cf. A000720, A258851. %K A258855 nonn %O A258855 0,5 %A A258855 _Alois P. Heinz_, Jun 12 2015