A129807 Primes congruent to +-7 mod 18.

7, 11, 29, 43, 47, 61, 79, 83, 97, 101, 137, 151, 173, 191, 223, 227, 241, 263, 277, 281, 313, 317, 331, 349, 353, 367, 389, 421, 439, 443, 457, 461, 479, 547, 569, 587, 601, 619, 641, 659, 673, 677, 691, 709, 727, 821, 839, 853, 857, 907, 911, 929, 947, 983, 997, 1019

Offset: 1

Author

N. J. A. Sloane, May 22 2007

Keywords

• nonn
• easy

Comments

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

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Emma Lehmer, On special primes, Pac. J. Math., 118 (1985), 471-478.

Crossrefs

Cf. A000040.

Cf. A001651, A061238, A061241.

Cf. A129805, A129806.

Programs

Magma

[ p: p in PrimesUpTo(1300) | p mod 18 in {7, 11} ]; // Vincenzo Librandi, Aug 14 2012

Mathematica

Select[Prime[Range[1000]],MemberQ[{7,11},Mod[ #,18]]&] (* Zak Seidov, May 23 2007 *)

Formula

Conjecture: Equals (A061241 UNION A061238) MINUS {2}. - R. J. Mathar, Jun 10 2007