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%I #9 Sep 08 2022 08:44:46
%S 1,21,252,2275,17052,111594,657419,3557256,17931459,85093393,
%T 383211885,1648114587,6803773998,27073141326,104199172863,
%U 389047640905,1412682672765,4999550830281,17277525329491,58400376126855,193361098926450,627924447630011,2002332877504113
%N Expansion of Product_{m >=1} (1+m*q^m)^21.
%H G. C. Greubel, <a href="/A022649/b022649.txt">Table of n, a(n) for n = 0..1000</a>
%t With[{nmax=50}, CoefficientList[Series[Product[(1+m*q^m)^21,{m,1,nmax}],{q,0,nmax}],q]] (* _G. C. Greubel_, Mar 20 2018 *)
%o (PARI) m=50; q='q+O('q^m); Vec(prod(n=1,m,(1+n*q^n)^21)) \\ _G. C. Greubel_, Mar 20 2018
%o (Magma) Coefficients(&*[(1+m*x^m)^21:m in [1..40]])[1..40] where x is PolynomialRing(Integers()).1; // _G. C. Greubel_, Mar 20 2018
%K nonn
%O 0,2
%A _N. J. A. Sloane_
%E Terms a(19) onward added by _G. C. Greubel_, Mar 20 2018