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

%I #7 Aug 06 2023 11:04:14

%S 1,-1,-1,4,1,-21,14,111,-195,-529,1837,1792,-14772,2300,105431,

%T -126697,-657427,1650427,3285795,-16211352,-8308737,135770125,

%U -79748628,-990431659,1700106664,6098396204,-20258923714,-27342511804,193913175511,12018867589

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

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

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

%Y Cf. A007440, A364761, A364762, A364763.

%Y Cf. A161634.

%K sign

%O 0,4

%A _Seiichi Manyama_, Aug 05 2023