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A306573
Numbers k such that 11^(k+7) + 7^(k+5) + 5^(k+3) + 3^(k+2) + 2^(k+1) + 1 is prime.
2
3, 5, 7, 81, 185, 254, 623, 1087, 2407, 7862, 8721, 9353, 13154
OFFSET
1,1
COMMENTS
a(14) > 41000. - Michael S. Branicky, Mar 25 2023
MATHEMATICA
ParallelMap[If[PrimeQ[11^(#+7) + 7^(#+5) + 5^(#+3) + 3^(#+2) + 2^(#+1) + 1], #, Nothing] &, Range@8000]
PROG
(PARI) is(n) = ispseudoprime(11^(n+7) + 7^(n+5) + 5^(n+3) + 3^(n+2) + 2^(n+1) + 1) \\ Felix Fröhlich, Mar 06 2019
CROSSREFS
Sequence in context: A291438 A056145 A119939 * A254925 A153138 A201270
KEYWORD
nonn,more,hard
AUTHOR
Mikk Heidemaa, Feb 24 2019
STATUS
approved