A113283 Even bisection of A113281: a(n) = A113281(2*n).

1, 3, 11, 51, 255, 1325, 7039, 37951, 206799, 1135969, 6279509, 34889553, 194664283, 1089943229, 6120967411, 34463104999, 194474062663, 1099571123853, 6227893795649, 35329149864161, 200691916063033, 1141489886332555

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Formula

G.f.: ( (1+x)/(1-x)/(1-6*x+x^2)*(1-x+(1-6*x+x^2)^(1/2))/2 )^(1/2).

a(n) ~ (1 + sqrt(2))^(2*n + 1/2) / (2*sqrt(Pi*n)). - Vaclav Kotesovec, Oct 18 2020

Prog

(PARI) {a(n)=local(x=X+X*O(X^n)); polcoeff( ((1+x)/(1-x)/(1-6*x+x^2)*(1-x+(1-6*x+x^2)^(1/2))/2)^(1/2), n, X)}

Crossrefs

Cf. A113281, A113282, A113284.

Sequence in context: A191341 A359146 A199212 * A326519 A127784 A112696

Adjacent sequences: A113280 A113281 A113282 * A113284 A113285 A113286

Keyword

nonn

Author

Paul D. Hanna, Oct 22 2005

Status

approved