The Gould numbers.

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =31a(5) =121a(6) =523a(7) =2469a(8) =12611a(9) =69161a(10) =404663a(11) =2512769a(12) =16485691a(13) =113842301a(14) =824723643a(15) =6249805129a(16) =49416246911a(17) =406754704841