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%I #20 Sep 08 2022 08:45:35
%S 19,61,103,229,271,313,397,439,523,607,691,733,859,1069,1153,1237,
%T 1279,1321,1447,1489,1531,1657,1699,1741,1783,1867,1951,1993,2161,
%U 2203,2287,2371,2539,2707,2749,2791,2833,2917,3001,3169,3253,3463,3547,3631,3673
%N Primes congruent to 19 mod 21.
%H Vincenzo Librandi, <a href="/A141897/b141897.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) ~ 12n log n. - _Charles R Greathouse IV_, Jul 02 2016
%t Select[Range[19,5000,21],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 04 2011 *)
%o (Magma) [ p: p in PrimesUpTo(5000) | p mod 21 eq 19 ]; // _Vincenzo Librandi_, Apr 05 2011
%o (PARI) is(n)=isprime(n) && n%21==19 \\ _Charles R Greathouse IV_, Jul 02 2016
%Y Cf. A000040, A124826.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Jul 11 2008