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 A049054 Numbers n such that 10^n + 3 is prime. 27
 1, 2, 5, 6, 11, 17, 18, 39, 56, 101, 105, 107, 123, 413, 426, 2607, 7668, 10470, 11021, 17753, 26927, 60776, 98288, 300476 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A102006 is another version of the same sequence. - N. J. A. Sloane, Jan 28 2010. Verified existing 21 terms. If another term exists, it is > 39456. - Robert Price, Aug 16 2010 LINKS Makoto Kamada, Prime numbers of the form 100...003. Henri & Renaud Lifchitz, PRP Records. Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers. FORMULA a(n) = A102006(n) + 1. EXAMPLE 5 is a member since 10^5 + 3 = 100003 is a prime. 6 is a member since 10^6 + 3 = 1000003 is a prime. MATHEMATICA Do[ If[ PrimeQ[ 10^n + 3], Print[n]], {n, 0, 18000}] (* Robert G. Wilson v Jun 15 2002 *) PROG (PARI) is(n)=isprime(10^n + 3) \\ Charles R Greathouse IV, Apr 28 2015 CROSSREFS Cf. A102006, A159352. Sequence in context: A180323 A103035 A088273 * A319140 A135476 A255310 Adjacent sequences:  A049051 A049052 A049053 * A049055 A049056 A049057 KEYWORD hard,more,nonn AUTHOR EXTENSIONS More terms from Robert G. Wilson v, Jun 15 2002 a(16) from Ray Chandler, Oct 09 2003 a(17)-a(20) from Robert G. Wilson v, Jan 18 2005 a(21)=26927 from Jason Earls, Jan 01 2008 a(22)=60776 from Robert Price, Jan 09 2011 a(23)=98288 from Robert Price, Mar 03 2011 a(24)=300476 from Edward A. Trice, Oct 21 2012 STATUS approved

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Last modified October 19 17:55 EDT 2018. Contains 316376 sequences. (Running on oeis4.)