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 A111405 #12 Oct 07 2017 10:10:33 %S A111405 0,0,0,1,-1,1,-1,1,0,0,-1,1,-1,1,0,1,-2,1,-1,1,0,0,-1,2,-1,0,0,0,-1,1, %T A111405 -1,1,0,0,0,1,-2,1,0,1,-2,1,-1,1,0,0,-1,1,0,0,0,0,-1,2,-1,1,-1,0,-1,2, %U A111405 -2,1,0,1,-1,0,-1,1,0,0,-1,1,-1,1,0,0,0,0,-1,1,1,-1,-1,2,-1,0,0,1,-2,2,-1,0,0,0,0,1,-2,1,0,1,-2 %N A111405 a(n) = f(f(n+1)) - f(f(n)), where f(0) = 0 and f(m) = bigomega(m) = A001222(m) for m > 0. %H A111405 Antti Karttunen, <a href="/A111405/b111405.txt">Table of n, a(n) for n = 0..20000</a> %o A111405 (PARI) %o A111405 f(n) = if(n==0,0,bigomega(n)); %o A111405 A111405(n) = f(f(n+1)) - f(f(n)); \\ _Antti Karttunen_, Oct 07 2017 %Y A111405 Cf. A001222, A111407. %K A111405 sign %O A111405 0,17 %A A111405 _N. J. A. Sloane_, Nov 12 2005 %E A111405 Description clarified by _Antti Karttunen_, Oct 07 2017