A069060 Product of divisors of 2^n + 1.

3, 5, 27, 17, 1089, 4225, 16641, 257, 69257922561, 1076890625, 4198401, 16785409, 67125249, 72075187834650625, 1238166730171084290520186881, 65537, 17180131329, 22301425772351053845871360015696103812890625, 274878955521

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..69

Formula

a(n) = Product_{d|2^n + 1} d. - Wesley Ivan Hurt, Jan 23 2017

a(n) = A007955(A000051(n)). - Michel Marcus, Jan 24 2017

Mathematica

Times@@Divisors[#]&/@(2^Range[20]+1) (* Harvey P. Dale, Mar 05 2020 *)

Prog

(PARI) a(n) = my(d=divisors(2^n+1)); prod(k=1, #d, d[k]); \\ Michel Marcus, Jan 24 2017

Crossrefs

Cf. A000051, A007955.

Sequence in context: A301315 A272148 A272224 * A273523 A307631 A307630

Adjacent sequences: A069057 A069058 A069059 * A069061 A069062 A069063

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 04 2002

Status

approved