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 A124495 #3 Mar 30 2012 18:37:01
%S A124495 1,1,2,3,8,14,43,81,283,556,2243,4512,21374,43469,243817,497217,
%T A124495 3289606,6697795,51583952,104698998,922789643,1867079621,18522929815,
%U A124495 37380015420,411572179999,828925168492,10014624164666,20140445929353
%N A124495 G.f.: A(x) = 1/[1-x - Sum_{n>=1} A001147(n)*x^(2n) ] where A001147(n) = (2n)!/(n!*2^n) is the double factorials.
%C A124495 Is this sequence equal to A076876 (meandric numbers for a river crossing two parallel roads at n points)?
%e A124495 G.f.: A(x) = 1/(1-x - x^2 - 3*x^4 - 15*x^6 - 105*x^8 - 945*x^10 -...).
%o A124495 (PARI) a(n)=polcoeff(1/(1-x-sum(k=1,n\2,(2*k)!/k!/2^k*x^(2*k))+x*O(x^n)),n)
%Y A124495 Cf. A001147.
%K A124495 nonn
%O A124495 0,3
%A A124495 _Paul D. Hanna_, Nov 04 2006