a(n) = smallest prime divisor of A138957(n).

Terms

a(0) =1a(1) =2a(2) =3a(3) =2a(4) =3a(5) =2a(6) =127a(7) =2a(8) =3a(9) =857a(10) =3a(11) =3a(12) =18503a(13) =3a(14) =3a(15) =43a(16) =3a(17) =3a(18) =17a(19) =2a(20) =2a(21) =2a(22) =2a(23) =2a(24) =2a(25) =2a(26) =2a(27) =2a(28) =2a(29) =3