A114301 Numbers k such that 2^k + 3^k + 5^k + 7^k is a prime number.

1, 3, 19, 1013, 4133, 9833, 30809, 64459

Offset

1,2

Comments

All terms are odd. - Robert Israel, May 03 2018

Links

Table of n, a(n) for n=1..8.

Example

2^3 + 3^3 + 5^3 + 7^3 = 503 (prime), thus 3 is in the sequence.

Maple

select(t -> isprime(2^t+3^t+5^t+7^t), [seq(i, i=1..10000, 2)]); # Robert Israel, May 03 2018

Mathematica

Do[If[PrimeQ[2^n+3^n+5^n+7^n], Print[n]], {n, 1, 5000}]

Crossrefs

Cf. A135168.

Sequence in context: A319190 A350121 A014015 * A258669 A192340 A326973

Adjacent sequences: A114298 A114299 A114300 * A114302 A114303 A114304

Keyword

hard,more,nonn

Author

Stefan Steinerberger, Feb 05 2006

Extensions

a(6) from Ryan Propper, Mar 24 2006

a(7) from Joao Carlos Leandro da Silva (zxawyh66(AT)yahoo.com), Jun 01 2009

a(8) from Michael S. Branicky, Jun 04 2024

Status

approved