a(n) = p(p(n)), p = partition numbers A000041.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =15a(6) =56a(7) =176a(8) =1002a(9) =5604a(10) =53174a(11) =526823a(12) =10619863a(13) =214481126a(14) =9035836076a(15) =476715857290