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 A045344 Primes congruent to {1, 2} mod 3. 21
 2, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Same as A045319, except for the 2nd term. - R. J. Mathar, Jan 30 2009 Primes of the form 3*n-+1. - Juri-Stepan Gerasimov, Jan 22 2010 Primes excluding 3. - Juri-Stepan Gerasimov, Apr 20 2010 Primes p such that p^2 + 2 is composite. 3 is the only prime p such that p^2 + 2 (= 11) is prime. All numbers p^2 + 2 for primes p = 2 and p > 3 are divisible by 3. - Jaroslav Krizek, Nov 25 2013 Primes p satisfying the equation gcd(sigma(p-1), p) = 1. - Lechoslaw Ratajczak, Aug 18 2018 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A000040(A065475(n)). - Reinhard Zumkeller, Dec 17 2009 MATHEMATICA Select[Prime[Range[150]], MemberQ[{1, 2}, Mod[#, 3]] &] (* Vladimir Joseph Stephan Orlovsky, Feb 18 2012 *) Drop[Prime@ Range@ 63, {2}] (* Robert G. Wilson v, Jun 04 2015 *) PROG (Magma) [p: p in PrimesUpTo(740)|p mod 3 in {1, 2}] // Vincenzo Librandi, Dec 18 2010 (PARI) a(n)=if(n<2, 2, prime(n+1)) \\ Charles R Greathouse IV, May 13 2011 CROSSREFS Cf. A000040, A045372, A045391. Sequence in context: A118751 A173494 A137519 * A087685 A020619 A165439 Adjacent sequences: A045341 A045342 A045343 * A045345 A045346 A045347 KEYWORD nonn,easy AUTHOR N. J. A. Sloane STATUS approved

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Last modified September 30 03:10 EDT 2023. Contains 365781 sequences. (Running on oeis4.)