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 A283684 Numbers k such that 3*10^k + 17 is prime. 0
 1, 2, 5, 6, 13, 17, 24, 29, 38, 43, 59, 92, 350, 365, 679, 1016, 2958, 4434, 6306, 8819, 11687, 13484, 22189, 43034, 69354, 78146, 78631, 150182 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 17 is prime (see Example section). a(29) > 2*10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 30w17. EXAMPLE 2 is in this sequence because 3*10^2 + 17 = 317 is prime. Initial terms and primes associated: a(1) = 1, 47; a(2) = 2, 317; a(3) = 5, 300017; a(4) = 6, 3000017; a(5) = 13, 30000000000017; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[3*10^# + 17] &] PROG (PARI) isok(n) = isprime((3*10^n + 17)); \\ Indranil Ghosh, Mar 14 2017 CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A342569 A028259 A327472 * A325285 A323348 A181314 Adjacent sequences: A283681 A283682 A283683 * A283685 A283686 A283687 KEYWORD nonn,more,hard AUTHOR Robert Price, Mar 14 2017 EXTENSIONS a(28) from Robert Price, Jul 27 2018 STATUS approved

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Last modified February 4 04:43 EST 2023. Contains 360046 sequences. (Running on oeis4.)