A228613 Least prime factor of (2n+1)^(2n+1)+2.

3, 29, 53, 3, 59, 97, 3, 23, 7, 3, 31, 19, 3, 5, 51131, 3, 5, 2003, 3, 229, 139, 3, 4215399123059, 5, 3, 179, 5, 3, 43, 7, 3, 103993, 61141, 3, 19961719, 13, 3, 2391083871204802979, 331, 3, 89, 30707, 3, 5, 601, 3, 5

Offset: 0

Author

M. F. Hasler and Stanislav Sykora, Feb 22 2014

Keywords

• nonn

Comments

Suggested by S. Sykora in a discussion in the OEIS users group on LinkedIn, since the numbers to be factored here are more "elementary" than those of the existing A216146, in turn motivated by A160360.

As of today, a(47) seems not yet known.

Links

• Factor DB, (2*n+1)^(2*n+1)+2.

Crossrefs

Cf. A216146, A160360.

Programs

Mathematica

Table[FactorInteger [((2 n + 1)^(2 n + 1) + 2)][[1, 1]], {n, 0, 46}] (* Vincenzo Librandi, Feb 24 2014 *)
FactorInteger[#^#+2][[1,1]]&/@Range[1,91,2] (* Harvey P. Dale, Aug 27 2023 *)

PARI

A228613=n->factor((2*n+1)^(2*n+1)+2)[1,1]

Formula

a(3k)=3 for all k >= 0.