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 A071738 #4 Mar 30 2012 16:49:26 %S A071738 1,1,2,6,19,62,207,704,2431,8502,30056,107236,385662,1396652,5088865, %T A071738 18642420,68624295,253706790,941630580,3507232740,13105289370, %U A071738 49114150020,184560753390,695267483664,2625197720454,9933364416572 %N A071738 Expansion of (1+x^3*C^4)*C, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108. %Y A071738 Essentially the same as A026012. %K A071738 nonn %O A071738 0,3 %A A071738 _N. J. A. Sloane_, Jun 06 2002