A303671 a(n) = [x^n] (6 / Sum_{k=0..n} (k+3)!*x^k)^(1/2).

1, -2, -4, -20, -140, -1192, -11656, -127072, -1517480, -19624400, -272656064, -4046157472, -63844717184, -1067307017600, -18846094327360, -350578477836160, -6854465726916640, -140564170444594880, -3017526392523529600, -67690323794750627200

Offset: 0

Author

Seiichi Manyama, Apr 28 2018

Keywords

• sign

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..446

Crossrefs

Cf. A077607, A303672, A303673.

Programs

Maple

[seq(coeff(series((factorial(3)/add(factorial(k+3)*x^k,k=0..n))^(1/2), x,30),x,n),n=0..25)]; # Muniru A Asiru, Apr 29 2018

PARI

N=66; x='x+O('x^N); Vec((3!/sum(k=0, N, (k+3)!*x^k))^(1/2))