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 A111581 #3 Mar 30 2012 18:36:50 %S A111581 1,1,2,2,3,3,4,5,6,7,8,8,9,9,10,10,11,12,12,14,14,15,16,16,17,17,18, %T A111581 19,19,21,20,21,22,22,24,24,25,26,27,29,29,31,32,32,34,34,35,36,37,38, %U A111581 39,40,41,42,44,44,45,46,47,48,49,49,50,50,51,51,52,53,53,55,55,56,57,57 %N A111581 G.f.: A(x) = ( G(x)^2 - G(x^2) - 2*x/(1-x^2) )/(4*x^2) where G(x) is the g.f. of A110627. %C A111581 A110627 is the bisection of A083952; surprisingly, the self-convolution of A110627 is congruent modulo 4 to A083952, which consists entirely of 1's and 2's. %Y A111581 Cf. A110627, A083952. %K A111581 nonn %O A111581 0,3 %A A111581 _Paul D. Hanna_, Aug 28 2005