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 A117266 #9 Sep 12 2024 07:50:01
%S A117266 1,2,6,37,497,14033,813857,95996993,22913626241,11034472530177,
%T A117266 10699863490757121,20863301244829828097,81721932792141693585409,
%U A117266 642577422892784159654154241,10136733849914528413869372612609
%N A117266 Row sums of triangle A117265.
%F A117266 a(n) = Sum_{k=0..n} (2*(n-k))!/((n-k)!*(n-k)!)*2^((n-k)*(n+k-3)/2).
%o A117266 (PARI) a(n)=sum(k=0,n,(2*(n-k))!/((n-k)!*(n-k)!)*2^((n-k)*(n+k-3)/2))
%Y A117266 Cf. A117265.
%K A117266 nonn
%O A117266 0,2
%A A117266 _Paul D. Hanna_, Mar 14 2006