G.f.: Sum_{k>=1} (x^(k*(k+1)) * Product_{j=1..k} (1 + x^j)/(1 - x^j)).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =2a(5) =2a(6) =3a(7) =4a(8) =6a(9) =8a(10) =10a(11) =12a(12) =15a(13) =18a(14) =22a(15) =28a(16) =34a(17) =42a(18) =52a(19) =62a(20) =75a(21) =90a(22) =106a(23) =126a(24) =150a(25) =176a(26) =208a(27) =246a(28) =288a(29) =338