a(n) = 1 + (number of partitions of n, n>0).

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =12a(7) =16a(8) =23a(9) =31a(10) =43a(11) =57a(12) =78a(13) =102a(14) =136a(15) =177a(16) =232a(17) =298a(18) =386a(19) =491a(20) =628a(21) =793a(22) =1003a(23) =1256a(24) =1576a(25) =1959a(26) =2437a(27) =3011a(28) =3719a(29) =4566