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 A270339 Numbers k such that (11*10^k + 19)/3 is prime. 502
 1, 2, 3, 9, 17, 18, 20, 24, 29, 36, 48, 114, 126, 135, 153, 170, 241, 363, 483, 579, 681, 948, 2483, 2798, 3081, 5137, 5640, 6890, 7080, 12600, 16929, 24253, 24793, 35546, 52956, 69645, 133831 (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 6 followed by the digits 73 is prime (see Example section). a(38) > 2*10^5. LINKS Makoto Kamada, Search for 36w73. EXAMPLE 3 is in this sequence because (11*10^3 + 19)/3 = 3673 is prime. Initial terms and primes associated: a(1) = 1, 43; a(2) = 2, 373; a(3) = 3, 3673; a(4) = 9, 3666666673; a(5) = 17, 366666666666666673, etc. MATHEMATICA Select[Range[0, 100000], PrimeQ[(11*10^# + 19)/3] &] PROG (PARI) is(n)=isprime((11*10^n + 19)/3) \\ Charles R Greathouse IV, Mar 16 2016 CROSSREFS Cf. A056654, A268448, A269303. Sequence in context: A086771 A156066 A143890 * A272057 A056658 A302164 Adjacent sequences:  A270336 A270337 A270338 * A270340 A270341 A270342 KEYWORD nonn,more AUTHOR Robert Price, Mar 15 2016 EXTENSIONS a(37) from Robert Price, Sep 16 2018 STATUS approved

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Last modified January 26 17:22 EST 2020. Contains 331280 sequences. (Running on oeis4.)