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 A258856 #4 Jun 12 2015 20:45:34 %S A258856 0,0,0,0,4,0,4,4,512,512,0,0,2304,4,32,80,12288,4,80,208,12288,32,16, %T A258856 208,4104,208,80,20736,9536,1,512,0,81920,208,1,4,1116,512,4,9536, %U A258856 1116,4,53,20,30848,944,4,32,137984,764,80,156,16092,2304,138240,332,936 %N A258856 Sixth pi-based arithmetic derivative of n. %H A258856 Alois P. Heinz, <a href="/A258856/b258856.txt">Table of n, a(n) for n = 0..10000</a> %F A258856 a(n) = A258851^6(n). %p A258856 with(numtheory): %p A258856 d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]): %p A258856 A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end: %p A258856 a:= n-> A(n, 6): %p A258856 seq(a(n), n=0..100); %Y A258856 Column k=6 of A258850. %Y A258856 Cf. A000720, A258851. %K A258856 nonn %O A258856 0,5 %A A258856 _Alois P. Heinz_, Jun 12 2015