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

%I #15 Sep 08 2022 08:45:46

%S 1,20,210,1539,8835,42294,175559,648925,2177361,6728260,19363355,

%T 52364721,134036525,326685790,761961825,1707940096,3692525360,

%U 7724060310,15675545395,30937970105,59507001114,111753986081

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

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

%H G. C. Greubel, <a href="/A162640/b162640.txt">Table of n, a(n) for n = 0..610</a>

%p 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

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

%o (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

%o (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

%K nonn

%O 0,2

%A _N. J. A. Sloane_, Dec 02 2009

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)