A161897 Prime numbers p for which k = (3^p - 3 * 3^((p + 1) / 2) - 6p + 6) / (3p^2 - 3p) is an integer

11, 23, 47, 59, 83, 107, 167, 179, 227, 263, 347, 359, 383, 467, 479, 503, 563, 587, 719, 839, 863, 887, 983, 1019, 1187, 1283, 1307, 1319, 1367, 1439, 1487, 1523, 1619, 1823, 1907, 2027, 2039, 2063, 2099, 2207, 2447, 2459, 2579, 2819, 2879, 2903, 2963, 2999

Offset

1,1

Comments

Superset of the inverse Sophie Germain primes (A005385): (p - 1) / 2 is almost always prime.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= p -> isprime(p) and
   (3&^p - 3 * 3&^((p + 1) / 2) - 6*p + 6) mod (3*p^2-3*p) = 0:
select(filter, [seq(i, i=3..10000, 2)]); # Robert Israel, Mar 31 2017

Crossrefs

Cf. A161896, A000040, A005385, A158034, A158035, A158036, A145918.

Sequence in context: A185005 A073024 A359387 * A282531 A309851 A145994

Adjacent sequences: A161894 A161895 A161896 * A161898 A161899 A161900

Keyword

easy,nonn

Author

Reikku Kulon, Jun 21 2009

Status

approved