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A049054
Numbers k such that 10^k + 3 is prime.
30
1, 2, 5, 6, 11, 17, 18, 39, 56, 101, 105, 107, 123, 413, 426, 2607, 7668, 10470, 11021, 17753, 26927, 60776, 98288, 300476, 509546
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
Henri & Renaud Lifchitz, PRP Records.
Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.
FORMULA
a(n) = A102006(n) + 1.
EXAMPLE
5 is a term since 10^5 + 3 = 100003 is a prime.
6 is a term 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
Sequence in context: A180323 A103035 A088273 * A319140 A336902 A373243
KEYWORD
hard,more,nonn
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) from Jason Earls, Jan 01 2008
a(22) from Robert Price, Jan 09 2011
a(23) from Robert Price, Mar 03 2011
a(24) from Edward A. Trice, Oct 21 2012
a(25) from Paul Bourdelais, Jan 28 2021
STATUS
approved