A066807 Integers of the form (2^k+1)/k.

3, 3, 57, 4971027, 29850020237398251227313, 17503832475167772961878049926333027042428946479619, 58167804601757508792865761341330650726830745576152064464908846133090363

Offset

1,1

Comments

a(n)=0 mod(3).

The next term (a(8)) has 152 digits and a(9) has 217 digits. - Harvey P. Dale, Oct 20 2014

Links

Table of n, a(n) for n=1..7.

Mathematica

Select[Table[(2^n+1)/n, {n, 300}], IntegerQ] (* Harvey P. Dale, Oct 20 2014 *)

Prog

(PARI) lista(nn) = {for (n=1, nn, if (type(v = (2^n+1)/n) == "t_INT", print1(v, ", ")); ); } \\ Michel Marcus, Nov 20 2013

Crossrefs

Cf. A006521.

Sequence in context: A290567 A339758 A100065 * A165497 A051752 A332786

Adjacent sequences: A066804 A066805 A066806 * A066808 A066809 A066810

Keyword

nonn

Author

Benoit Cloitre, Jan 19 2002

Status

approved