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 A071747 #4 Mar 30 2012 16:49:26 %S A071747 1,2,5,14,43,136,443,1478,5027,17368,60788,215084,768094,2764880, %T A071747 10021721,36546310,133990755,493606680,1826192640,6782469540, %U A071747 25278252810,94512157680,354397639830,1332454176924,5022040887822 %N A071747 Expansion of (1+x^4*C^2)*C^2, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108. %Y A071747 First differences of A067294. %K A071747 nonn %O A071747 0,2 %A A071747 _N. J. A. Sloane_, Jun 06 2002