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A161897 Prime numbers p for which k = (3^p - 3 * 3^((p + 1) / 2) - 6p + 6) / (3p^2 - 3p) is an integer 7
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

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

Sequence in context: A068231 A185005 A073024 * A282531 A145994 A217047

Adjacent sequences:  A161894 A161895 A161896 * A161898 A161899 A161900

KEYWORD

easy,nonn

AUTHOR

Reikku Kulon, Jun 21 2009

STATUS

approved

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Last modified January 18 13:38 EST 2019. Contains 319271 sequences. (Running on oeis4.)