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 A294396 Numbers k such that 12*10^k + 1 is prime. 0
 0, 2, 38, 80, 9230, 25598 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS k must be even since 12*10^k + 1 is divisible by 11 if k is odd. - Robert G. Wilson v, Feb 12 2018 a(7) > 27440. - Robert G. Wilson v, Feb 17 2018 LINKS EXAMPLE 13 and 1201 are prime, so 0 and 2 are the initial values. MATHEMATICA ParallelMap[ If[ PrimeQ[12*10^# +1], #, Nothing] &, 2 + 6Range@ 4500] (* Robert G. Wilson v, Feb 13 2018 *) PROG (PARI) isok(k) = isprime(12*10^k + 1); \\ Altug Alkan, Mar 04 2018 CROSSREFS Cf. A001562, A096507, A056797, A056807, A056806, A102940, A056805, A056804, A096508, A102975, A289051, A099017, A295325, A273002, A102945, A282456, A267420. Sequence in context: A050899 A068401 A173026 * A075459 A050248 A105645 Adjacent sequences:  A294393 A294394 A294395 * A294397 A294398 A294399 KEYWORD nonn,more AUTHOR Patrick A. Thomas, Feb 12 2018 EXTENSIONS a(5) from Robert G. Wilson v, Feb 12 2018 a(6) from Robert G. Wilson v, Feb 13 2018 STATUS approved

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Last modified October 13 16:34 EDT 2019. Contains 327966 sequences. (Running on oeis4.)