A371892 G.f. A(x) satisfies A(x) = 1 + x/A(x) * (1 + A(x)^4).

1, 2, 4, 24, 112, 688, 4032, 25856, 165888, 1103616, 7412480, 50699776, 350087168, 2444208128, 17198686208, 121945948160, 870026493952, 6242802761728, 45016506564608, 326071359897600, 2371312632397824, 17307835567636480, 126743329792327680

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Formula

a(n) = (-1)^(n-1) * (1/n) * Sum_{k=0..n} binomial(n,k) * binomial(2*n-4*k-2,n-1) for n > 0.

Prog

(PARI) a(n) = if(n==0, 1, (-1)^(n-1)*sum(k=0, n, binomial(n, k)*binomial(2*n-4*k-2, n-1))/n);

Crossrefs

Cf. A112478, A348957, A364394, A364395, A366363.

Sequence in context: A232205 A170931 A317999 * A164313 A087981 A002875

Adjacent sequences: A371889 A371890 A371891 * A371893 A371895 A371897

Keyword

nonn

Author

Seiichi Manyama, Apr 11 2024

Status

approved