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A162646 G.f. is the polynomial (Product_{k=1..21} (1 - x^(3*k)))/(1-x)^21. 1
1, 21, 231, 1770, 10605, 52899, 228458, 877383, 3054744, 9783004, 29146359, 81511080, 215547605, 542233395, 1304195220, 3012135316, 6704660676, 14428720986, 30104266381, 61042236486, 120549237600, 232303223681 (list; graph; refs; listen; history; text; internal format)
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..672

MAPLE

m:=21: 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@@(1-x^(3*Range[21]))/(1-x)^21, {x, 0, 50}], x] (* G. C. Greubel, Jul 06 2018 *)

PROG

(PARI) x='x+O('x^50); A = prod(k=1, 21, (1-x^(3*k)))/(1-x)^21; Vec(A) \\ G. C. Greubel, Jul 06 2018

(MAGMA) m:=50; R<x>:=PowerSeriesRing(Integers(), m); F:=(&*[(1-x^(3*k)): k in [1..21]])/(1-x)^21; Coefficients(R!(F)); // G. C. Greubel, Jul 06 2018

CROSSREFS

Sequence in context: A188354 A064322 A126902 * A247615 A010973 A022586

Adjacent sequences:  A162643 A162644 A162645 * A162647 A162648 A162649

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 02 2009

STATUS

approved

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Last modified January 24 09:58 EST 2022. Contains 350534 sequences. (Running on oeis4.)