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 A323040 Numbers k such that 391*2^k+1 is prime. 0
 4, 20, 28, 40, 88, 92, 328, 1052, 1420, 2888, 3944, 5888, 22544, 154912, 716668 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Ray Ballinger, Proth Search Page Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for 300 < k < 600 Wilfrid Keller, List of primes k.2^n - 1 for k < 300 Eric Weisstein's World of Mathematics, Proth Prime MATHEMATICA Select[Range[1000], PrimeQ[391*2^# + 1] &] (* Robert Price, Jan 03 2019 *) CROSSREFS Sequence in context: A097251 A202070 A198831 * A259755 A317249 A181433 Adjacent sequences:  A323037 A323038 A323039 * A323041 A323042 A323043 KEYWORD nonn,more,hard AUTHOR Robert Price, Jan 03 2019 STATUS approved

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Last modified November 25 11:32 EST 2020. Contains 338623 sequences. (Running on oeis4.)