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A273601
Numbers k such that (11^k - 9^k)/2 is prime.
3
5, 31, 271, 929, 2789, 4153
OFFSET
1,1
COMMENTS
All terms are prime.
The corresponding primes: 51001, 95780952266636767336259095696501, ...
a(7) > 50000. - Michael S. Branicky, Nov 11 2024
MATHEMATICA
Select[Range[1, 10000], PrimeQ[(11^# - 9^#)/2] &]
PROG
(PARI) for(n=1, 10000, if(isprime((11^n - 9^n)/2), print1(n, ", ")))
KEYWORD
nonn,more,hard
AUTHOR
STATUS
approved