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 A109245 #2 Mar 30 2012 18:59:08 %S A109245 1,1,5,15,54,193,708,2627,9846,37178,141223,539047,2065813,7943706, %T A109245 30634329,118433821,458867295,1781267606,6926405025,26973935420, %U A109245 105189301334,410707352869,1605379739149,6281519778025,24601184635436 %N A109245 Diagonal sums of number triangle A109244. %F A109245 G.f.: 1/((1-xc(x)-2x^2c(x)^2)(1-x^2c(x))), c(x) the g.f. of A000108. %K A109245 easy,nonn %O A109245 0,3 %A A109245 _Paul Barry_, Jun 23 2005