G.f.: Sum_{n>=0} (n+1)*(n+2)/2 * x^n * (1 + x^n)^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =10a(4) =27a(5) =21a(6) =64a(7) =36a(8) =105a(9) =85a(10) =171a(11) =78a(12) =359a(13) =105a(14) =372a(15) =346a(16) =573a(17) =171a(18) =1105a(19) =210a(20) =1116a(21) =1009a(22) =1134a(23) =300a(24) =3237a(25) =456a(26) =1743a(27) =2386a(28) =3375a(29) =465