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
Programs
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Mathematica
Table[(-1)^n*2^n*n!*LegendreP[n, 1/2], {n, 0, 20}] (* Vaclav Kotesovec, May 06 2017 *) -
PARI
x='x+O('x^55); Vec(serlaplace(1/sqrt(1+2*x+4*x^2)))
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
Comments