a(n+1) = a(n)-th composite and a(1) = 13.

Terms

a(0) =13a(1) =22a(2) =34a(3) =50a(4) =70a(5) =95a(6) =126a(7) =165a(8) =213a(9) =272a(10) =341a(11) =424a(12) =524a(13) =640a(14) =778a(15) =938a(16) =1127a(17) =1345a(18) =1596a(19) =1886a(20) =2217a(21) =2596a(22) =3031a(23) =3523a(24) =4086a(25) =4724a(26) =5445a(27) =6259a(28) =7176a(29) =8205