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A023215
Primes p such that 4*p + 7 is also prime.
1
3, 13, 19, 31, 43, 61, 103, 109, 139, 163, 241, 271, 313, 373, 379, 499, 523, 601, 613, 631, 643, 673, 709, 733, 739, 751, 769, 811, 823, 829, 883, 1021, 1033, 1051, 1063, 1069, 1129, 1171, 1231, 1249, 1291, 1381, 1459, 1483, 1531, 1549, 1579, 1621, 1663
OFFSET
1,1
COMMENTS
Except for the first term, all terms are congruent to 1 (mod 6). - John Cerkan, Sep 07 2016
LINKS
MAPLE
A023215:=n->`if`(isprime(n) and isprime(4*n+7), n, NULL): seq(A023215(n), n=1..3*10^3); # Wesley Ivan Hurt, Sep 07 2016
MATHEMATICA
Select[Prime[Range[300]], PrimeQ[4#+7]&] (* Harvey P. Dale, Jan 21 2011 *)
PROG
(Magma) [n: n in PrimesUpTo(500) | IsPrime(4*n+7)]; // Vincenzo Librandi, Nov 19 2010
CROSSREFS
Subsequence of primes of A089986.
Sequence in context: A252090 A079419 A117300 * A185069 A023239 A229494
KEYWORD
nonn,easy
STATUS
approved