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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

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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.

PROG

(PARI) a(n) = 2^(-(2*(n-1)-1-logint(n-1, 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

URL: https://oeis.org/A160473

⇱ A160473 - OEIS