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

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =20a(6) =42a(7) =75a(8) =141a(9) =259a(10) =466a(11) =799a(12) =1427a(13) =2443a(14) =4169a(15) =7049a(16) =11863a(17) =19605a(18) =32518a(19) =53184a(20) =86579a(21) =140018a(22) =225380a(23) =359739a(24) =572864a(25) =905903a(26) =1426270a(27) =2234952a(28) =3488313a(29) =5416403