Smallest prime factor of the n-th Jacobsthal number: a(n) = A020639(A001045(n)), with a(1)=a(2)=1.

Terms

a(0) =1a(1) =1a(2) =3a(3) =5a(4) =11a(5) =3a(6) =43a(7) =5a(8) =3a(9) =11a(10) =683a(11) =3a(12) =2731a(13) =43a(14) =3a(15) =5a(16) =43691a(17) =3a(18) =174763a(19) =5a(20) =3a(21) =23a(22) =2796203a(23) =3a(24) =11a(25) =2731a(26) =3a(27) =5a(28) =59a(29) =3