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%I #12 Sep 08 2022 08:45:35
%S 67,109,151,193,277,487,571,613,739,823,907,991,1033,1117,1201,1327,
%T 1453,1579,1621,1663,1747,1789,1831,1873,1999,2083,2251,2293,2377,
%U 2503,2671,2713,2797,3049,3217,3259,3301,3343,3469,3511,3637,3847,3889,3931,4057
%N Primes congruent to 4 mod 21.
%H Vincenzo Librandi, <a href="/A141889/b141889.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) ~ 12n log n. - _Charles R Greathouse IV_, Jul 03 2016
%t Select[Range[4,5000,21],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2011*)
%o (Magma) [p: p in PrimesUpTo(6000) | p mod 21 eq 4 ]; // _Vincenzo Librandi_, Aug 16 2012
%o (PARI) is(n)=isprime(n) && n%21==4 \\ _Charles R Greathouse IV_, Jul 03 2016
%Y Cf. A000040, A124826.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Jul 11 2008
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