A124826 - OEIS

%I #14 Sep 08 2022 08:45:28

%S 43,127,211,337,379,421,463,547,631,673,757,883,967,1009,1051,1093,

%T 1303,1429,1471,1597,1723,1933,2017,2143,2269,2311,2437,2521,2647,

%U 2689,2731,2857,3067,3109,3319,3361,3529,3571,3613,3697,3739,3823,3907,4159,4201

%N Primes congruent to 1 mod 21.

%H Vincenzo Librandi, <a href="/A124826/b124826.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[1,5000,21],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2011*)

%o (Magma) [p: p in PrimesUpTo(5000) | p mod 21 eq 1 ]; // _Vincenzo Librandi_, Aug 14 2012

%o (PARI) is(n)=isprime(n) && n%21==1 \\ _Charles R Greathouse IV_, Jul 01 2016

%Y Cf. A000040, A141881.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, Jul 11 2008