A151816 a(n) = (2*n)! - ((2*n-1)!!)^2.

0, 1, 15, 495, 29295, 2735775, 370945575, 68916822975, 16813959537375, 5214921734397375, 2004231846526284375, 934957186489800849375, 520444368391989625959375, 340788940288324502208609375, 259324006920606914270844234375, 226933251813970116856323617109375, 226305693647403205116652558922109375

Offset

0,3

Comments

This was (incorrectly) proposed as a formula for A001818(2n).

Links

Table of n, a(n) for n=0..16.

Tewodros Amdeberhan, Adriana Duncan, Victor H. Moll, and Vaishavi Sharma, Filter integrals for orthogonal polynomials, arXiv:2012.05040 [math.CA], 2020.

Formula

a(n) = A000142(2*n) - A001147(n)^2.

a(n) = A010050(n) - A001818(n).

Maple

seq((2*n)! - doublefactorial(2*n-1)^2, n=0..16); # Georg Fischer, Apr 19 2024

Crossrefs

Cf. A000142, A010050, A001147, A001818.

Bisection of A088979.

Sequence in context: A208624 A013433 A013435 * A013431 A013432 A285765

Adjacent sequences: A151813 A151814 A151815 * A151817 A151818 A151819

Keyword

nonn

Author

N. J. A. Sloane, Jul 03 2009

Extensions

Definition corrected by Georg Fischer, Apr 18 2024

Status

approved