A093793 Numbers n such that 5^n+4^(n-1) is prime.

2, 6, 22, 94, 622, 910, 1058, 1306, 4430, 18914, 23654, 35630, 52846, 63498, 85630

Offset

1,1

Comments

a(16) > 10^5. - Robert Price, Mar 08 2016

Links

Table of n, a(n) for n=1..15.

Example

22 is a member since 522+421 = 2388583837526729 which is a prime number.

Mathematica

Do[ If[ PrimeQ[5^n + 4^(n - 1)], Print[n]], {n, 5000}]

Prog

(PARI) is(n)=isprime(5^n+4^(n-1)) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Cf. A082103, A093717, A093765, A096185, A093794, A093795, A096186.

Sequence in context: A187251 A193763 A301385 * A087959 A292096 A006871

Adjacent sequences: A093790 A093791 A093792 * A093794 A093795 A093796

Keyword

nonn

Author

Herman H. Rosenfeld (herm3(AT)pacbell.net), May 17 2004

Extensions

More terms from Robert G. Wilson v, Jun 18 2004

a(10)-a(15) from Robert Price, Mar 08 2016

Status

approved