A162640 G.f. is the polynomial (Product_{k=1..20} (1 - x^(3*k)))/(1-x)^20.

1, 20, 210, 1539, 8835, 42294, 175559, 648925, 2177361, 6728260, 19363355, 52364721, 134036525, 326685790, 761961825, 1707940096, 3692525360, 7724060310, 15675545395, 30937970105, 59507001114, 111753986081

Offset

0,2

Comments

This is a row of the triangle in A162499. Only finitely many terms are nonzero.

Links

G. C. Greubel, Table of n, a(n) for n = 0..610

Maple

m:=20: seq(coeff(series(mul((1-x^(3*k)), k=1..m)/(1-x)^m, x, n+1), x, n), n=0..21); # Muniru A Asiru, Jul 07 2018

Mathematica

CoefficientList[Series[Times@@Table[1-x^n, {n, 3, 60, 3}]/(1-x)^20, {x, 0, 30}], x] (* Harvey P. Dale, May 06 2012 *)

Prog

(PARI) x='x+O('x^50); A = prod(k=1, 20, (1-x^(3*k)))/(1-x)^20; Vec(A) \\ G. C. Greubel, Jul 06 2018
(Magma) m:=50; R<x>:=PowerSeriesRing(Integers(), m); F:=(&*[(1-x^(3*k)): k in [1..20]])/(1-x)^20; Coefficients(R!(F)); // G. C. Greubel, Jul 06 2018

Crossrefs

Sequence in context: A094311 A353895 A353884 * A060853 A010972 A126905

Adjacent sequences: A162637 A162638 A162639 * A162641 A162642 A162643

Keyword

nonn

Author

N. J. A. Sloane, Dec 02 2009

Status

approved