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A302123
Numbers k such that 6*k^k - 5 is prime.
6
2, 3, 4, 7, 8, 9, 33, 138, 251, 467, 489, 9894
OFFSET
1,1
COMMENTS
a(13) > 50000. - Robert Price, Jan 04 2020
MATHEMATICA
Select[Range[1, 1000], PrimeQ[6*#^# - 5] &] (* Vaclav Kotesovec, Apr 02 2018 *)
PROG
(PARI) for(n=0, 300, if(isprime(6*n^n-5), print1(n", ")))
CROSSREFS
Numbers k such that b*k^k - b + 1 is prime: A301521 (b=4), this sequence (b=6).
Sequence in context: A111116 A113318 A056033 * A286337 A047547 A014456
KEYWORD
nonn,more,hard
AUTHOR
Seiichi Manyama, Apr 01 2018
EXTENSIONS
a(10)-a(11) from Vaclav Kotesovec, Apr 02 2018
a(12) from Robert Price, Jan 04 2020
STATUS
approved