Least prime factor of concatenation of first n odd numbers.

Terms

a(0) =1a(1) =13a(2) =3a(3) =23a(4) =37a(5) =3a(6) =11617a(7) =5a(8) =3a(10) =29a(11) =3a(12) =5a(13) =11a(14) =3a(16) =17a(17) =3a(18) =7a(19) =13a(20) =3a(21) =131a(22) =5a(23) =3a(24) =11a(26) =3a(27) =5a(28) =7a(29) =3a(30) =181a(31) =41a(32) =3