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 A295837 Numbers k such that (37*10^k + 341)/9 is prime. 0
 1, 2, 4, 7, 10, 11, 17, 20, 65, 70, 811, 947, 1099, 1487, 1540, 6617, 15067, 18433, 19063, 31462, 131270 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k > 1, numbers such that the digit 4 followed by k-2 occurrences of the digit 1 followed by the digits 49 is prime (see Example section). a(22) > 2*10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 41w49 EXAMPLE 2 is in this sequence because (37*10^2 + 341)/9 = 449 is prime. Initial terms and primes associated: a(1) = 1, 79; a(2) = 2, 449; a(3) = 4, 41149; a(4) = 7, 41111149; a(5) = 10, 41111111149; etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(37*10^# + 341)/9] &] CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A153383 A278997 A342782 * A321972 A288482 A177093 Adjacent sequences:  A295834 A295835 A295836 * A295838 A295839 A295840 KEYWORD nonn,more,hard AUTHOR Robert Price, Nov 28 2017 EXTENSIONS a(21) from Robert Price, Aug 14 2018 STATUS approved

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Last modified May 21 00:36 EDT 2022. Contains 353886 sequences. (Running on oeis4.)