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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =5a(5) =7a(6) =11a(7) =14a(8) =17a(9) =24a(10) =30a(11) =37a(12) =48a(13) =58a(14) =71a(15) =92a(16) =108a(17) =129a(18) =160a(19) =188a(20) =225a(21) =273a(22) =319a(23) =377a(24) =449a(25) =524a(26) =612a(27) =721a(28) =836a(29) =969