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 A168357 #2 Mar 30 2012 18:37:20
%S A168357 1,2,5,20,112,768,5984,50856,460180,4366076,42988488,436066232,
%T A168357 4532973676,48095557700,519247705968,5690272928520,63172884082028,
%U A168357 709373555125356,8046263496489260,92089662771965492,1062482514810065752
%N A168357 Self-convolution of A006664, which is the number of irreducible systems of meanders.
%F A168357 G.f.: A(x) = x/Series_Reversion(x*F(x)^2) where F(x) = g.f. of A001246, which is the squares of Catalan numbers.
%F A168357 G.f.: A(x) = F(x/A(x))^2 where A(x*F(x)^2) = F(x)^2 where F(x) = g.f. of A001246.
%e A168357 G.f.: A(x) = 1 + 2*x + 5*x^2 + 20*x^3 + 112*x^4 + 768*x^5 +...
%e A168357 A(x)^(1/2) = 1 + x + 2*x^2 + 8*x^3 + 46*x^4 + 322*x^5 + 2546*x^6 +...+ A006664(n)*x^n +...
%e A168357 G.f. satisfies: A(x*F(x)^2) = F(x)^2 where F(x) = g.f. of A001246:
%e A168357 F(x) = 1 + x + 4*x^2 + 25*x^3 + 196*x^4 + 1764*x^5 + 17424*x^6 +...+ A000108(n)^2*x^n +...
%e A168357 F(x)^2 = 1 + 2*x + 9*x^2 + 58*x^3 + 458*x^4 + 4120*x^5 + 40569*x^6 +...+ A168358(n)*x^n +...
%o A168357 (PARI) {a(n)=local(C_2=vector(n+1, m, (binomial(2*m-2, m-1)/m)^2)); polcoeff(x/serreverse(x*Ser(C_2)^2), n)}
%Y A168357 Cf. A168358, A168344, A001246, A006664, A000108.
%K A168357 nonn
%O A168357 0,2
%A A168357 _Paul D. Hanna_, Nov 23 2009