A160473 The p(n) sequence that is associated with the Eta triangle A160464.

3, 30, 315, 11340, 311850, 12162150, 638512875, 86837751000, 7424627710500, 779585909602500, 98617617564716250, 14792642634707437500, 2596108782391155281250, 527010082825404522093750, 122529844256906551386796875, 64695757767646659132228750000

Offset

2,1

Links

Table of n, a(n) for n=2..17.

Formula

a(n) = 2^(-(2*(n-1)-1-floor(log(n-1)/log(2))))*(2*n-1)! for n = 2, 3, 4, ... .

Prog

(PARI) vector(20, n, n++; 2^(-(2*(n-1)-1-floor(log(n-1)/log(2))))*(2*n-1)!) \\ Michel Marcus, Jul 06 2015
(Magma) [2^(-(2*(n-1)-1-Floor(Log(n-1)/Log(2))))*Factorial(2*n-1)  : n in [2..30]]; // Vincenzo Librandi, Jul 06 2015

Crossrefs

A160464 is the Eta triangle.

Equals 3*(n-2)!*A000457(n-2)/A054243(n-1)

Equals 2^(-A049039(n-1))*(2*n-1)!

Cf. The pg(n) sequence A162440. - Johannes W. Meijer, Jul 06 2009

Sequence in context: A163475 A200142 A339626 * A144283 A229299 A365158

Adjacent sequences: A160470 A160471 A160472 * A160474 A160475 A160476

Keyword

easy,nonn

Author

Johannes W. Meijer, May 24 2009

Status

approved