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 A272999 Numbers k such that (11*10^k + 49)/3 is prime. 0
 1, 2, 4, 5, 7, 10, 11, 16, 18, 21, 22, 30, 41, 69, 83, 128, 166, 190, 262, 263, 353, 496, 1398, 1793, 2806, 9722, 15733, 32420, 61095, 77909, 110496 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 6 followed by the digits 83 is prime (see Example section). a(32) > 3*10^5. LINKS Table of n, a(n) for n=1..31. Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 36w83. EXAMPLE 4 is in this sequence because (11*10^4 + 49)/3 = 36683 is prime. Initial terms and associated primes: a(1) = 1, 53; a(2) = 2, 383: a(3) = 4, 36683; a(4) = 5, 366683; a(5) = 7, 36666683, etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(11*10^# + 49)/3] &] PROG (PARI) is(n)=ispseudoprime((11*10^n + 49)/3) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A153766 A319301 A093013 * A278490 A188029 A187951 Adjacent sequences: A272996 A272997 A272998 * A273000 A273001 A273002 KEYWORD nonn,more AUTHOR Robert Price, May 12 2016 EXTENSIONS a(31) from Robert Price, Jul 19 2018 STATUS approved

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Last modified June 12 14:48 EDT 2024. Contains 373331 sequences. (Running on oeis4.)