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

0,1

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

Table of n, a(n) for n=0..46.

Factor DB, (2*n+1)^(2*n+1)+2.

Formula

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

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 *)

Prog

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

Crossrefs

Cf. A216146, A160360.

Sequence in context: A072306 A303137 A364076 * A071150 A107189 A059761

Adjacent sequences: A228610 A228611 A228612 * A228614 A228615 A228616

Keyword

nonn

Author

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

Status

approved