

A107083


Integers n such that 10^n + 31 is prime.


25



1, 2, 3, 14, 18, 44, 54, 89, 469, 2060, 2985, 6197, 16452, 19393, 21205, 49657, 74670, 76374
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OFFSET

1,2


COMMENTS

The next term, if one exists, is >100000.  Robert Price, Apr 26 2011
See Kamada link  primecount.txt for terms, primesize.txt for discovery details including proofs of primality  search on "10031".


LINKS

Table of n, a(n) for n=1..18.
Makoto Kamada, List of nearrepdigitrelated prime numbers.
Index entries for primes involving repunits.


EXAMPLE

For n = 3 we get 10^3 + 31 = 1000 + 31 = 1031, which is prime.


MATHEMATICA

a={}; Do[If[PrimeQ[p=10^n+31], AppendTo[a, n]], {n, 0, 6*10^2}]; a (* Vladimir Joseph Stephan Orlovsky, Aug 07 2008 *)


CROSSREFS

Cf. A049054, A088274, A088275, A095688, A108052, A108050, A108049, A108054.
Sequence in context: A041010 A041733 A212112 * A266694 A284928 A294405
Adjacent sequences: A107080 A107081 A107082 * A107084 A107085 A107086


KEYWORD

more,nonn,changed


AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Jun 08 2005


EXTENSIONS

16452 and 19393 from Robert Price, Mar 22 2010
Additional term (21205) from Robert Price, May 24 2010
Missing term (6197) added by Robert Price, Dec 07 2010
Edited by Ray Chandler, Dec 23 2010
a(16)=49657 from Robert Price, Dec 31 2010
a(17)=74670 from Robert Price, Jan 29 2011
a(18)=76374 from Robert Price, Mar 03 2011


STATUS

approved



