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%I #20 Sep 08 2022 08:45:35
%S 13,97,139,181,223,307,349,433,601,643,727,769,811,853,937,1021,1063,
%T 1231,1399,1483,1567,1609,1693,1777,1861,1987,2029,2113,2239,2281,
%U 2617,2659,2953,3037,3079,3121,3163,3331,3373,3457,3499,3541,3583,3709,3793,3877
%N Primes congruent to 13 mod 21.
%H Vincenzo Librandi, <a href="/A141894/b141894.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) ~ 12n log n. - _Charles R Greathouse IV_, Jul 01 2016
%t Select[Range[13,5000,21],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 04 2011 *)
%o (Magma) [ p: p in PrimesUpTo(5000) | p mod 21 eq 13 ]; // _Vincenzo Librandi_, Apr 05 2011
%o (PARI) is(n)=isprime(n) && n%21==13 \\ _Charles R Greathouse IV_, Jul 01 2016
%Y Cf. A000040, A124826.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Jul 11 2008
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