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 A258859 #4 Jun 12 2015 20:47:10 %S A258859 0,0,0,0,4,0,4,4,81920,81920,0,0,622592,4,512,2304,4931584,4,2304, %T A258859 12288,4931584,512,208,12288,193644,12288,2304,8322048,423168,0,81920, %U A258859 0,38944768,12288,0,4,37880,81920,4,423168,37880,4,80,208,2298880,43632,4,512 %N A258859 Ninth pi-based arithmetic derivative of n. %H A258859 Alois P. Heinz, <a href="/A258859/b258859.txt">Table of n, a(n) for n = 0..10000</a> %F A258859 a(n) = A258851^9(n). %p A258859 with(numtheory): %p A258859 d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]): %p A258859 A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end: %p A258859 a:= n-> A(n, 9): %p A258859 seq(a(n), n=0..100); %Y A258859 Column k=9 of A258850. %Y A258859 Cf. A000720, A258851. %K A258859 nonn %O A258859 0,5 %A A258859 _Alois P. Heinz_, Jun 12 2015