G.f.: Sum_{k>=1} k! * x^(k^2) / (1 - x^k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =1a(5) =3a(6) =1a(7) =3a(8) =7a(9) =3a(10) =1a(11) =9a(12) =1a(13) =3a(14) =7a(15) =27a(16) =1a(17) =9a(18) =1a(19) =27a(20) =7a(21) =3a(22) =1a(23) =33a(24) =121a(25) =3a(26) =7a(27) =27a(28) =1a(29) =129