

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
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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

Table of n, a(n) for n=1..24.
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 * A135476 A255310 A051217
Adjacent sequences: A049051 A049052 A049053 * A049055 A049056 A049057


KEYWORD

hard,more,nonn


AUTHOR

G. L. Honaker, Jr.


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



