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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS 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 Adjacent sequences: A306570 A306571 A306572 * A306574 A306575 A306576 KEYWORD nonn,more,hard AUTHOR Mikk Heidemaa, Feb 24 2019 STATUS approved

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Last modified February 4 07:13 EST 2023. Contains 360046 sequences. (Running on oeis4.)