A203427 a(n) = w(n+1)/(4*w(n)), where w = A203426.

-3, 48, -1000, 25920, -806736, 29360128, -1224440064, 57600000000, -3018173044480, 174359297654784, -11011033460963328, 754709361539940352, -55801305000000000000, 4427218577690292387840, -375183514207494575620096, 33824309717272203758665728, -3232463698006063164519284736, 326417514496000000000000000000

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..345

Formula

a(n) = (1/4) * (n+1) * (-2*(n+2))^n. - Andrei Asinowski, Nov 03 2015

Mathematica

(* First program *)
f[j_]:= 1/(2 j + 2); z = 12;
v[n_]:= Product[Product[f[k] - f[j], {j, k-1}], {k, 2, n}];
1/Table[v[n], {n, z}]               (* A203426 *)
Table[v[n]/(4 v[n + 1]), {n, z}]    (* A203427 *)
(* Second program *)
Table[(-2*(n+2))^n*(n+1)/4, {n, 20}] (* G. C. Greubel, Dec 05 2023 *)

Prog

(Magma) [(-2*(n+2))^n*(n+1)/4: n in [1..20]]; // G. C. Greubel, Dec 05 2023
(SageMath) [(-2*(n+2))^n*(n+1)/4 for n in range(1, 21)] # G. C. Greubel, Dec 05 2023

Crossrefs

Cf. A203425, A203426.

Sequence in context: A270005 A218382 A195635 * A365651 A320668 A319732

Adjacent sequences: A203424 A203425 A203426 * A203428 A203429 A203430

Keyword

sign

Author

Clark Kimberling, Jan 02 2012

Extensions

Name corrected by Andrei Asinowski, Nov 03 2015

Terms a(14) onward added by G. C. Greubel, Dec 05 2023

Status

approved