Expansion of Product_{k>=1} (1 + x^k)^(k*(k+1)*(2*k-1)/2).

Terms

a(0) =1a(1) =1a(2) =9a(3) =39a(4) =136a(5) =511a(6) =1785a(7) =6139a(8) =20404a(9) =66406a(10) =211418a(11) =660752a(12) =2030172a(13) =6139231a(14) =18300573a(15) =53823451a(16) =156344596a(17) =448886205a(18) =1274840165a(19) =3583595734a(20) =9976530997a(21) =27520998775a(22) =75262394273a(23) =204130567402a(24) =549318633095