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A215487
Numbers n such that (7^n - 2^n)/5 is prime.
1
3, 7, 19, 79, 431, 1373, 1801, 2897, 46997, 341063, 508867, 720497, 846913
OFFSET
1,1
COMMENTS
All terms are prime.
a(14) > 10^6.
LINKS
Jon Grantham and Andrew Granville, Fibonacci primes, primes of the form 2^n-k and beyond, arXiv:2307.07894 [math.NT], 2023.
MATHEMATICA
Select[ Prime[ Range[1, 100000] ], PrimeQ[ ((7^# - 2^#)/5 ]& ]
PROG
(PARI) is(n)=ispseudoprime((7^n-2^n)/5) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
hard,more,nonn
AUTHOR
Robert Price, Aug 12 2012
EXTENSIONS
a(10)-a(13) from Jon Grantham, Jul 29 2023
STATUS
approved