A034271 a(n) = f(n,n+4) where f is given in A034261.

0, 1, 15, 125, 814, 4641, 24388, 121380, 581400, 2707386, 12339569, 55304535, 244567050, 1069784625, 4637437560, 19951650840, 85290143760, 362608278750, 1534330716750, 6465583372794, 27147098904156, 113618646478106, 474177584413720, 1973918305023000, 8198353999348240

Offset

0,3

Links

Table of n, a(n) for n=0..24.

Formula

From Amiram Eldar, Sep 04 2025: (Start)

a(n) = binomial(2*n+4, n+5)*(n^2+5*n+1)/(n+6);

a(n) ~ 2^(2*n+4) * sqrt(n/Pi). (End)

Mathematica

a[n_] := Binomial[2*n + 4, n + 5]*(n^2 + 5*n + 1)/(n + 6); Array[a, 25, 0] (* Amiram Eldar, Sep 04 2025 *)

Crossrefs

Cf. A034261.

Sequence in context: A393326 A349295 A027839 * A171220 A071080 A193365

Adjacent sequences: A034268 A034269 A034270 * A034272 A034273 A034274

Keyword

nonn

Author

Clark Kimberling

Extensions

Corrected and extended by N. J. A. Sloane, Apr 21 2000

Status

approved