a(1) = 1. For n >= 2, add to a(n-1) its prime or nonprime index to obtain a(n).

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =12a(6) =19a(7) =27a(8) =45a(9) =76a(10) =131a(11) =163a(12) =201a(13) =356a(14) =641a(15) =757a(16) =891a(17) =1628a(18) =2998a(19) =5567a(20) =10400a(21) =19526a(22) =36838a(23) =69770a(24) =132623a(25) =145002a(26) =276582a(27) =528994a(28) =1014241a(29) =1948927