A262539 a(n) = coefficient of x^n in the expansion of Product_{k>=1} (1-x^k)^(3*n).

1, -3, 9, -12, -99, 1107, -7038, 33345, -113643, 151593, 1547469, -17376120, 112734378, -544200660, 1884830229, -2551628817, -26299018683, 298555990425, -1956243650733, 9538198578972, -33464928293199, 47571625958796, 452674080810576, -5260288747038957, 34841458485708282, -171603777320158968

Offset: 0

Author

N. J. A. Sloane, Oct 04 2015

Keywords

• sign

Crossrefs

Bisections: A262540, A262541.

Programs

Maple

C3:=proc(k) local t1,n;
t1:=mul((1-x^n)^(3*k),n=1..k+2);
series(t1,x,k+1);
coeff(%,x,k);
end;
[seq(C3(i),i=0..30)];