Smallest prime factor of composites in the sequence A000051(n) = 2^n+1.

Terms

a(0) =3a(1) =3a(2) =5a(3) =3a(4) =3a(5) =5a(6) =3a(7) =17a(8) =3a(9) =5a(10) =3a(11) =3a(12) =5a(13) =3a(14) =17a(15) =3a(16) =5a(17) =3a(18) =97a(19) =3a(20) =5a(21) =3a(22) =17a(23) =3a(24) =5a(25) =3a(26) =641a(27) =3a(28) =5a(29) =3