a(2) = a(3) = 1; for n >3, a(n) = smallest prime factor of n-th Tribonacci number.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =7a(5) =13a(6) =2a(7) =2a(8) =3a(9) =149a(10) =2a(11) =2a(12) =3a(13) =5a(14) =2a(15) =2a(16) =103a(17) =13a(18) =2a(19) =2a(20) =5a(21) =3a(22) =2a(23) =2a(24) =3a(25) =3a(26) =2a(27) =2a(28) =23a(29) =5