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 A140186 #2 Mar 31 2012 10:31:22 %S A140186 2,1,2,2,1,2,3,5,2,2,2,5,2,2,3,15,1,5,2,5,3,2,3,15,3,2,6,4,2,4,7,51,1, %T A140186 4,3,14,1,2,4,14,1,6,4,4,3,3,6,52,2,5,2,7,1,15,4,13,3,2,2,13,4,2,18, %U A140186 267,1,4,3,5,1,9,7,50,2,2,4,4,2,6,8,52,15,2,3,15,1,2,3,14,1,10,3,5,4 %N A140186 Number of connected groupoids (categories all of whose morphisms are invertible) with n more morphisms than objects. %C A140186 a(n) >= A000001(n+1) (number of groups of order n+1). %F A140186 a(0) = 2 and if n>0, a(n) = sum(A000001((n+k)/(k^2)),k^2|n+k). (see formula for A140185) %Y A140186 Cf. A140185, A140187, A140188. %K A140186 nonn %O A140186 0,1 %A A140186 _Benoit Jubin_, May 12 2008