A161897 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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