%I #14 Sep 08 2022 08:46:08
%S 2,3,5,7,11,13,17,19,2,8,10,16,20,1,5,11,17,19,4,8,10,16,20,5,13,17,
%T 19,2,4,8,1,5,11,13,2,4,10,16,20,5,11,13,2,4,8,10,1,13,17,19,2,8,10,
%U 20,5,11,17,19,4,8,10,20,13,17,19,2,16,1,11,13,17,2,10
%N Primes modulo 21.
%H Vincenzo Librandi, <a href="/A242121/b242121.txt">Table of n, a(n) for n = 1..1000</a>
%t Mod[Prime[Range[100]], 21]
%o (Magma) [p mod(21): p in PrimesUpTo(500)];
%o (PARI) a(n) = prime(n) % 21; \\ _Michel Marcus_, May 05 2014
%o (Sage) [mod(p, 21) for p in primes(500)] # _Bruno Berselli_, May 05 2014
%Y Cf. similar sequences listed in A242119.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, May 05 2014
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