A392587 Expansion of 1 / ((1-x)^3 - x^4)^2.

1, 6, 21, 56, 128, 270, 552, 1122, 2280, 4612, 9243, 18330, 36027, 70352, 136752, 264860, 511280, 983796, 1887232, 3610248, 6889317, 13117918, 24928625, 47287656, 89551088, 169324234, 319698936, 602813046, 1135232744, 2135427564, 4012500479, 7531906034, 14124749751

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-13,0,5,-2,-1).

Formula

a(n) = Sum_{k=0..floor(n/4)} (k+1) * binomial(n-k+5,n-4*k).

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 13*a(n-4) + 5*a(n-6) - 2*a(n-7) - a(n-8).

Prog

(PARI) my(N=40, x='x+O('x^N)); Vec(1/((1-x)^3-x^4)^2)

Crossrefs

Cf. A292324, A392552, A392588, A392589.

Cf. A107068.

Sequence in context: A346893 A337895 A145134 * A256571 A247904 A074745

Adjacent sequences: A392584 A392585 A392586 * A392588 A392589 A392590

Keyword

nonn,easy

Author

Seiichi Manyama, Jan 17 2026

Status

approved