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G.f. satisfies A(x) = 1 + x*A(x)^2/(1 - x^3*A(x)^4).
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%I #10 Aug 28 2023 10:51:59

%S 1,1,2,5,15,50,177,650,2449,9412,36761,145518,582556,2354557,9594898,

%T 39378259,162619316,675258452,2817643240,11808576745,49683880754,

%U 209786559004,888676860191,3775654643360,16084818268474,68694452578325,294053067958011

%N G.f. satisfies A(x) = 1 + x*A(x)^2/(1 - x^3*A(x)^4).

%F a(n) = Sum_{k=0..floor(n/3)} binomial(n-2*k-1,k) * binomial(2*n-2*k+1,n-3*k)/(2*n-2*k+1).

%o (PARI) a(n) = sum(k=0, n\3, binomial(n-2*k-1, k)*binomial(2*n-2*k+1, n-3*k)/(2*n-2*k+1));

%Y Cf. A364739, A365246.

%Y Cf. A218251, A364161, A364833.

%K nonn

%O 0,3

%A _Seiichi Manyama_, Aug 28 2023