A135108 Integers n such that 10^n+39 is a prime number.
2, 3, 4, 6, 8, 12, 20, 72, 196, 676, 1528, 1923, 5244, 5379, 6308, 21222, 81778
Offset: 1
Examples
6 is a member: 10^6+39 = 1000000+39 = 1000039, which is a prime number.
Links
- Makoto Kamada, List of near-repdigit-related prime numbers. (See primecount.txt for terms, primesize.txt for discovery details, including probable or proved primes - search on "10039")
- Index entries for primes involving repunits.
Programs
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Magma
[n: n in [0..500] |IsPrime(10^n+39)]; // Vincenzo Librandi, Sep 24 2016
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Mathematica
Select[Range[2000], PrimeQ[10^# + 39] &] (* G. C. Greubel, Sep 23 2016 *)
Extensions
a(11)-a(12) from Harvey P. Dale, May 25 2008
a(13)-a(16) from Robert Price, Jan 30 2010
Edited by Ray Chandler, Dec 23 2010
a(17) from Robert Price, Mar 03 2011