login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228130 Numbers n such that (18^n + 5^n)/23 is prime. 1
61, 227, 233, 239, 613, 2213, 7507, 13691 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

a(9) > 10^5.

LINKS

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

MATHEMATICA

k=18; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 9592}]

PROG

(PARI) is(n)=ispseudoprime((18^n+5^n)/23) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A057184, A128353, A225397, A227046.

Sequence in context: A038643 A273364 A297731 * A142267 A034863 A251312

Adjacent sequences: A228127 A228128 A228129 * A228131 A228132 A228133

KEYWORD

hard,more,nonn

AUTHOR

Robert Price, Aug 11 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 3 02:45 EST 2023. Contains 360024 sequences. (Running on oeis4.)