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Primes congruent to +-7 mod 18.
6

%I #15 Sep 08 2022 08:45:30

%S 7,11,29,43,47,61,79,83,97,101,137,151,173,191,223,227,241,263,277,

%T 281,313,317,331,349,353,367,389,421,439,443,457,461,479,547,569,587,

%U 601,619,641,659,673,677,691,709,727,821,839,853,857,907,911,929,947,983,997,1019

%N Primes congruent to +-7 mod 18.

%C Also: primes that are sums of three consecutive terms of A001651. These sum to either 3k+1+3k+2+3k+4=9k+7, candidates for A061241, or 3k+2+3k+4+3k+5=9k+11, candidates for A061238. - _R. J. Mathar_, Jun 10 2007

%H Vincenzo Librandi, <a href="/A129807/b129807.txt">Table of n, a(n) for n = 1..1000</a>

%H Emma Lehmer, <a href="https://projecteuclid.org/euclid.pjm/1102706454">On special primes</a>, Pac. J. Math., 118 (1985), 471-478.

%F Conjecture: Equals (A061241 UNION A061238) MINUS {2}. - _R. J. Mathar_, Jun 10 2007

%t Select[Prime[Range[1000]],MemberQ[{7,11},Mod[ #,18]]&] (* _Zak Seidov_, May 23 2007 *)

%o (Magma) [ p: p in PrimesUpTo(1300) | p mod 18 in {7, 11} ]; // _Vincenzo Librandi_, Aug 14 2012

%Y Cf. A000040.

%Y Cf. A001651, A061238, A061241.

%Y Cf. A129805, A129806.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, May 22 2007