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 A023218 Primes p such that 5*p + 4 is also prime. 15
 3, 5, 11, 17, 29, 47, 53, 71, 83, 89, 101, 113, 131, 167, 251, 257, 263, 281, 311, 389, 419, 461, 467, 479, 491, 509, 521, 557, 563, 587, 593, 599, 617, 641, 659, 677, 743, 797, 809, 827, 857, 881, 929, 977, 983, 1019, 1061, 1103, 1187, 1217, 1259, 1277, 1289, 1319 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Except for the first term, all terms are congruent to 5 (mod 6). - John Cerkan, Sep 07 2016 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..2000 MAPLE A023218:=n->`if`(isprime(n) and isprime(5*n+4), n, NULL): seq(A023218(n), n=1..2*10^3); # Wesley Ivan Hurt, Sep 07 2016 MATHEMATICA lst={}; Do[If[PrimeQ[n]&&PrimeQ[5*n+4], AppendTo[lst, n]], {n, 13^3}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 08 2008 *) Select[Prime[Range[300]], PrimeQ[5#+4]&] (* Harvey P. Dale, Dec 31 2013 *) PROG (MAGMA) [n: n in [0..1000] | IsPrime(n) and IsPrime(5*n+4)]; // Vincenzo Librandi, Nov 20 2010 CROSSREFS Subsequence of primes of A024897. Sequence in context: A078864 A208574 A342230 * A073022 A129694 A147015 Adjacent sequences:  A023215 A023216 A023217 * A023219 A023220 A023221 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified July 30 23:12 EDT 2021. Contains 346365 sequences. (Running on oeis4.)