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 A282277 Numbers k such that (23*10^k + 97)/3 is prime. 0
 3, 6, 11, 14, 20, 38, 55, 206, 1327, 1676, 1715, 1814, 2030, 2406, 2599, 3251, 4493, 5066, 6029, 8745, 24918, 26672, 70363, 77556 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For k>1, numbers such that the digit 7 followed by k-2 occurrences of the digit 6 followed by the digits 99 is prime (see Example section). a(25) > 10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 76w99. EXAMPLE 6 is in this sequence because (23*10^6 + 97)/3 = 7666699 is prime. Initial terms and primes associated: a(1) = 3, 7699; a(2) = 6, 7666699; a(3) = 11, 766666666699; a(4) = 14, 766666666666699; a(5) = 20, 766666666666666666699; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(23*10^# + 97)/3] &] CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A047924 A267519 A200182 * A122599 A015823 A049620 Adjacent sequences:  A282274 A282275 A282276 * A282278 A282279 A282280 KEYWORD nonn,more,hard AUTHOR Robert Price, Feb 10 2017 STATUS approved

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Last modified March 22 17:25 EDT 2019. Contains 321422 sequences. (Running on oeis4.)