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%I #14 Aug 20 2024 14:51:14
%S 83,269,331,641,827,1013,1447,1571,2129,2377,2687,2749,3121,3307,3617,
%T 3803,3989,4051,4423,4547,4733,4919,5167,5477,5849,6221,6469,6779,
%U 6841,7027,7151,7213,7523,8081,8329,8887,9011,9631,9817,9941,10313,10499,11057,11119
%N Primes congruent to 21 mod 31.
%H Vincenzo Librandi, <a href="/A142025/b142025.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) ~ 30n log n. - _Charles R Greathouse IV_, Jul 03 2016
%t Select[Range[21,20000,31],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 30 2011 *)
%t Select[Prime[Range[1500]],Mod[#,31]==21&] (* _Harvey P. Dale_, Aug 20 2024 *)
%o (Magma) [p: p in PrimesUpTo(12000) | p mod 31 eq 21 ]; // _Vincenzo Librandi_, Aug 17 2012
%o (PARI) is(n)=isprime(n) && n%31==21 \\ _Charles R Greathouse IV_, Jul 03 2016
%Y Cf. A000040, A142005, A142006, A142023.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Jul 11 2008