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 A262937 Numbers k such that (28*10^k - 13) / 3 is prime. 0
 0, 1, 2, 4, 5, 8, 10, 14, 17, 20, 33, 64, 80, 152, 158, 166, 194, 196, 198, 901, 971, 1289, 1595, 2921, 14390, 28781, 35840 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For k>1, numbers such that the digit 9 followed by k-2 occurrences of the digit 3 followed by the digits 29 is prime (see Example section). a(28) > 2*10^5. LINKS Makoto Kamada, Factorization of near-repdigit-related numbers. Makoto Kamada, Search for 93w29. EXAMPLE 2 is in this sequence because (28*10^2 - 13) / 3 = 929 is prime. Initial terms and primes associated: a(1) = 0, 5; a(2) = 1, 89; a(3) = 2, 929; a(4) = 4, 93329; a(5) = 5, 933329, etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(28*10^# - 13) / 3] &] PROG (PARI) is(n)=ispseudoprime((28*10^n - 13)/3) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. Sequence in context: A259711 A182195 A092265 * A249508 A163295 A101274 Adjacent sequences:  A262934 A262935 A262936 * A262938 A262939 A262940 KEYWORD nonn,more AUTHOR Robert Price, Sep 23 2016 STATUS approved

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Last modified November 28 13:18 EST 2020. Contains 338724 sequences. (Running on oeis4.)