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 A180075 #8 Mar 30 2012 18:52:41 %S A180075 1,1,2,1,3,2,1,2,1,2,3,1,1,4,3,2,1,4,2,4,1,2,1,3,2,1,2,3,4,1,1,4,2,1, %T A180075 4,3,4,1,5,3,2,1,4,1,2,3,5,6,1,4,3,1,6,1,2,4,6,1,4,2,1,6,5,5,3,1 %N A180075 If A015910(m) is a power of 2, append log_2(A015910(m)) to the sequence. %F A180075 A015910(m)=2^(a(n)). %t A180075 f[n_] := Log2@ PowerMod[2, n, n]; Select[f@ Range@ 100, IntegerQ] %Y A180075 Cf. A000079, A015910. %K A180075 nonn %O A180075 1,3 %A A180075 _Juri-Stepan Gerasimov_, Jan 14 2011