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 A258858 #4 Jun 12 2015 20:46:43 %S A258858 0,0,0,0,4,0,4,4,12288,12288,0,0,81920,4,208,512,622592,4,512,2304, %T A258858 622592,208,80,2304,52056,2304,512,1050624,114752,0,12288,0,4931584, %U A258858 2304,0,4,11900,12288,4,114752,11900,4,32,80,423168,9936,4,208,3679488,3084 %N A258858 Eighth pi-based arithmetic derivative of n. %H A258858 Alois P. Heinz, <a href="/A258858/b258858.txt">Table of n, a(n) for n = 0..10000</a> %F A258858 a(n) = A258851^8(n). %p A258858 with(numtheory): %p A258858 d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]): %p A258858 A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end: %p A258858 a:= n-> A(n, 8): %p A258858 seq(a(n), n=0..100); %Y A258858 Column k=8 of A258850. %Y A258858 Cf. A000720, A258851. %K A258858 nonn %O A258858 0,5 %A A258858 _Alois P. Heinz_, Jun 12 2015