A139781 Primes of form (5^n - 2^n)/3.

7, 1031, 25999, 406898311, 6357828601279, 24253192047278040531416551, 57824115865893569813730623892812790134879, 22587545260114675708488599968932468124811638399, 5514537417020184499142724613799550869468811634476741679

Offset

1,1

Links

Table of n, a(n) for n=1..9.

Example

(5^2-2^2)/3=7, (5^5-2^5)/3=1031, (5^7-2^7)/3=25999, ...

Mathematica

a={}; Do[p=(5^n-2^n)/3; If[PrimeQ[p], AppendTo[a, p]], {n, 20^2}]; Print[a];
Select[Table[(5^n-2^n)/3, {n, 0, 500}], PrimeQ] (* Harvey P. Dale, Aug 12 2012 *)

Crossrefs

Sequence in context: A013544 A250914 A004807 * A101072 A203583 A259251

Adjacent sequences: A139778 A139779 A139780 * A139782 A139783 A139784

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, May 16 2008

Extensions

More terms from Harvey P. Dale, Aug 12 2012

Status

approved