A182827 E.g.f. 1/sqrt(1+2x+4x^2).

1, -1, -1, 21, -111, -345, 14895, -143955, -760095, 49774095, -699437025, -5221460475, 458621111025, -8457966542025, -81662774418225, 8999266227076125, -205480756062957375, -2434383666448358625, 322739182334471277375, -8786388514658364484875

Offset

0,4

Comments

First column of A182826.

Links

Table of n, a(n) for n=0..19.

Formula

D-finite with recurrence: a(n) +(2n-1)*a(n-1) +4*(n-1)^2*a(n-2)=0. - R. J. Mathar, Nov 17 2011

Mathematica

Table[(-1)^n*2^n*n!*LegendreP[n, 1/2], {n, 0, 20}] (* Vaclav Kotesovec, May 06 2017 *)

Prog

(PARI) x='x+O('x^55); Vec(serlaplace(1/sqrt(1+2*x+4*x^2)))

Crossrefs

Sequence in context: A069307 A157886 A039456 * A364268 A255285 A157265

Adjacent sequences: A182824 A182825 A182826 * A182828 A182829 A182830

Keyword

sign,easy

Author

Paul Barry, Dec 05 2010

Status

approved