A147667 Primes of the form 5^n - 4^n.

61, 1136791005963704961126617632861, 173472015290681763212224222187425603741981, 31861838222649045530727106406255616308752331078816472270207782250106896363274089867800367051529351065966102374800998198276889145001421

Offset

1,1

Comments

All terms are odd, and if n is even, then 5^n - 4^n is divisible by 3. [Vincenzo Librandi, Nov 25 2010]

The next term (a(5)) has 156 digits. - Harvey P. Dale, May 14 2022

Links

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

Example

5^3 - 4^3 = 125 - 64 = 61.

Maple

select(isprime, [seq(5^n - 4^n, n=0..200)]); # Muniru A Asiru, Mar 04 2018

Mathematica

lst={}; Do[p=5^n-4^n; If[PrimeQ[p], AppendTo[lst, p]], {n, 6!}]; lst
Select[Table[5^n-4^n, {n, 300}], PrimeQ] (* Harvey P. Dale, May 14 2022 *)

Prog

(GAP) Filtered(List([1..200], n->5^n - 4^n), IsPrime); # Muniru A Asiru, Mar 04 2018

Crossrefs

Cf. A059802 (corresponding n).

Sequence in context: A087513 A176272 A173418 * A022084 A362452 A110823

Adjacent sequences: A147664 A147665 A147666 * A147668 A147669 A147670

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Nov 10 2008

Status

approved