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 A136650 #2 Mar 30 2012 18:37:09
%S A136650 1,2,5,20,148,2208,67904,4264960,541216768,137984868352,
%T A136650 70507295670272,72128242290524160,147646152060442771456,
%U A136650 604610628447525580832768,4952364915780360673188380672,81134591384874923825347187179520
%N A136650 Self-convolution of A006125(n) = 2^{n(n-1)/2}.
%F A136650 a(n) = Sum_{k=0..n} 2^{ k(k-1)/2 + (n-k)(n-k-1)/2 }.
%o A136650 (PARI) a(n)=sum(k=0,n,2^(k*(k-1)/2 + (n-k)*(n-k-1)/2))
%K A136650 nonn
%O A136650 0,2
%A A136650 _Paul D. Hanna_, Jan 16 2008