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A093793 Numbers n such that 5^n+4^(n-1) is prime. 19
2, 6, 22, 94, 622, 910, 1058, 1306, 4430, 18914, 23654, 35630, 52846, 63498, 85630 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 11 00:55 EDT 2022. Contains 356046 sequences. (Running on oeis4.)