This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A161897 #14 Jul 22 2025 06:42:36 %S A161897 11,23,47,59,83,107,167,179,227,263,347,359,383,467,479,503,563,587, %T A161897 719,839,863,887,983,1019,1187,1283,1307,1319,1367,1439,1487,1523, %U A161897 1619,1823,1907,2027,2039,2063,2099,2207,2447,2459,2579,2819,2879,2903,2963,2999 %N A161897 Prime numbers p for which k = (3^p - 3 * 3^((p + 1) / 2) - 6p + 6) / (3p^2 - 3p) is an integer. %C A161897 Superset of the inverse Sophie Germain primes (A005385): (p - 1) / 2 is almost always prime. %H A161897 Robert Israel, <a href="/A161897/b161897.txt">Table of n, a(n) for n = 1..10000</a> %p A161897 filter:= p -> isprime(p) and %p A161897 (3&^p - 3 * 3&^((p + 1) / 2) - 6*p + 6) mod (3*p^2-3*p) = 0: %p A161897 select(filter, [seq(i,i=3..10000,2)]); # _Robert Israel_, Mar 31 2017 %Y A161897 Cf. A161896, A000040, A005385, A158034, A158035, A158036, A145918. %K A161897 easy,nonn %O A161897 1,1 %A A161897 _Reikku Kulon_, Jun 21 2009