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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 5

%I

%S 11,23,47,59,83,107,167,179,227,263,347,359,383,467,479,503,563,587,

%T 719,839,863,887,983,1019,1187,1283,1307,1319,1367,1439,1487,1523,

%U 1619,1823,1907,2027,2039,2063,2099,2207,2447,2459,2579,2819,2879,2903,2963,2999

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

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

%H Robert Israel, <a href="/A161897/b161897.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= p -> isprime(p) and

%p (3&^p - 3 * 3&^((p + 1) / 2) - 6*p + 6) mod (3*p^2-3*p) = 0:

%p select(filter, [seq(i,i=3..10000,2)]); # _Robert Israel_, Mar 31 2017

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

%K easy,nonn

%O 1,1

%A _Reikku Kulon_, Jun 21 2009

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Last modified July 25 08:07 EDT 2021. Contains 346285 sequences. (Running on oeis4.)