A108329 Integers k such that 10^k - 27 is prime.

2, 4, 7, 14, 20, 22, 29, 31, 40, 80, 85, 224, 767, 952, 3592, 4016, 4187, 9239, 17684, 20716, 30791

Offset

1,1

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99973".

The next term, if one exists, is > 100000. - Robert Price, Apr 25 2011

Links

Table of n, a(n) for n=1..21.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

Example

k = 7 is a term because 10^7 - 27 = 10000000 - 27 = 9999973, which is prime.

Crossrefs

Cf. A089675, A095714, A092767, A176987.

Sequence in context: A367266 A018505 A280430 * A057264 A045514 A102957

Adjacent sequences: A108326 A108327 A108328 * A108330 A108331 A108332

Keyword

nonn,more

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Jun 30 2005

Extensions

a(18)-a(19) from Kamada data by Robert Price, Dec 10 2010

a(20)-a(21) from Robert Price, Dec 15 2010

Edited by Ray Chandler, Dec 23 2010

Status

approved