login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128343 Numbers n such that (14^n + 5^n)/19 is prime. 11
3, 7, 17, 79, 17477, 19319, 49549 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

a(8) > 10^5. - Robert Price, May 20 2013

LINKS

Table of n, a(n) for n=1..7.

MATHEMATICA

k=14; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

PROG

(PARI) is(n)=isprime((14^n+5^n)/19) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342. Cf. A004061, A082182, A121877, A059802. Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Sequence in context: A264765 A247196 A246764 * A106877 A041949 A222452

Adjacent sequences:  A128340 A128341 A128342 * A128344 A128345 A128346

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 27 2007

EXTENSIONS

a(5)-a(7) from Robert Price, May 20 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 23 19:45 EST 2020. Contains 331175 sequences. (Running on oeis4.)