Expansion of Product_{k>=1} (1 - 3*x^k).

Terms

a(0) =1a(1) =-3a(2) =-3a(3) =6a(4) =6a(5) =15a(6) =-12a(7) =-3a(8) =-30a(9) =-48a(10) =6a(11) =-12a(12) =15a(13) =78a(14) =186a(15) =-21a(16) =168a(17) =42a(18) =42a(19) =-246a(20) =-408a(21) =-156a(22) =-399a(23) =-552a(24) =-498a(25) =-246a(26) =213a(27) =1248a(28) =-318a(29) =1608