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 A108654 Numbers k such that 10^k - 117 is prime. 0
 3, 4, 6, 7, 9, 15, 27, 40, 72, 134, 170, 204, 237, 240, 285, 288, 592, 613, 1443, 1524, 2289, 2292 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE If k=3 then 10^k - 117 = 883 (prime). If k=40 then 10^k - 117 = 9999999999999999999999999999999999999883 (prime). MAPLE a := proc (n) if isprime(10^n-117) = true then n else end if end proc; seq(a(n), n = 1 .. 1500); # Emeric Deutsch, Jul 09 2007 MATHEMATICA Select[Range[3, 2500], PrimeQ[10^#-117]&]  (* Harvey P. Dale, Feb 18 2011 *) PROG (PARI) is(n)=ispseudoprime(10^n-117) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Sequence in context: A066271 A127594 A094604 * A131530 A285379 A102093 Adjacent sequences:  A108651 A108652 A108653 * A108655 A108656 A108657 KEYWORD nonn,hard,more AUTHOR Parthasarathy Nambi, Jul 06 2005 EXTENSIONS More terms from Emeric Deutsch, Jul 09 2007 More terms from Harvey P. Dale, Feb 18 2011 STATUS approved

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Last modified October 16 20:22 EDT 2019. Contains 328102 sequences. (Running on oeis4.)