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 A245156 #8 Jul 16 2014 09:21:20
%S A245156 1,1,1,4,13,51,234,1205,6861,42696,287893,2088343,16195822,133582909,
%T A245156 1166593665,10746339324,104072482781,1056515903547,11213782563474,
%U A245156 124152537651877,1430804512710901,17131971790847440,212761333257548485,2736258689605227615,36389676240341831766
%N A245156 G.f.: Sum_{n>=0} x^n/((1+x)^(2*n)*(1 - (2*n)*x)).
%C A245156 Inspired by Peter Bala's formula in A229046.
%H A245156 Vaclav Kotesovec, <a href="/A245156/b245156.txt">Table of n, a(n) for n = 0..400</a>
%e A245156 G.f.: A(x) = 1 + x + x^2 + 4*x^3 + 13*x^4 + 51*x^5 + 234*x^6 +...
%e A245156 where
%e A245156 A(x) = 1 + x/((1+x)^2*(1-2*x)) + x^2/((1+x)^4*(1-4*x)) + x^3/((1+x)^6*(1-6*x))+ x^4/((1+x)^8*(1-8*x))+ x^5/((1+x)^10*(1-10*x)) + x^6/((1+x)^12*(1-12*x)) +...
%o A245156 (PARI) {a(n)=polcoeff( sum(m=0, n, x^m/((1+x)^(2*m)*(1 - 2*m*x) +x*O(x^n))), n)}
%o A245156 for(n=0, 30, print1(a(n), ", "))
%Y A245156 Cf. A229046, A245157.
%K A245156 nonn
%O A245156 0,4
%A A245156 _Paul D. Hanna_, Jul 15 2014