A072343 a(n) = 2^(n-1) * Sum_{k=0..n} (n+k)! / k!^2.

3, 28, 320, 4272, 65632, 1149312, 22712832, 501216000, 12225264128, 326574262272, 9478749110272, 296914161754112, 9979741990993920, 358151267772203008, 13664955628675399680, 552220995731872481280, 23558112944407296737280, 1057816659215007783321600, 49862751709864361113681920

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..398

Mathematica

a[n_] := 2^(n-1) * Sum[(n+k)! / k!^2, {k, 0, n}]; Array[a, 20] (* Amiram Eldar, Apr 29 2025 *)

Crossrefs

Sequence in context: A199754 A277507 A176335 * A292845 A212032 A352383

Adjacent sequences: A072340 A072341 A072342 * A072344 A072345 A072346

Keyword

easy,nonn

Author

Benoit Cloitre, Jul 31 2002

Status

approved