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

Terms

a(0) =1a(1) =4a(2) =14a(3) =36a(4) =89a(5) =200a(6) =434a(7) =898a(8) =1810a(9) =3548a(10) =6810a(11) =12816a(12) =23719a(13) =43250a(14) =77795a(15) =138244a(16) =242920a(17) =422510a(18) =727907a(19) =1243094a(20) =2105493a(21) =3538936a(22) =5905481a(23) =9787810a(24) =16118588a(25) =26383244a(26) =42936039a(27) =69491436a(28) =111884015a(29) =179239648