a(n) = [(x*y)^n] Product_{k>=1} 1 / (1 - x^k - y^k)^k.

Terms

a(0) =1a(1) =2a(2) =16a(3) =78a(4) =426a(5) =1940a(6) =9300a(7) =40530a(8) =177940a(9) =749788a(10) =3137352a(11) =12865488a(12) =52425432a(13) =211336062a(14) =848099898a(15) =3385259588a(16) =13475690578a(17) =53504526568a(18) =212146065506a(19) =840218845230