This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A242120 #17 Dec 12 2024 09:29:41
%S A242120 2,3,5,7,11,13,17,19,3,9,11,17,1,3,7,13,19,1,7,11,13,19,3,9,17,1,3,7,
%T A242120 9,13,7,11,17,19,9,11,17,3,7,13,19,1,11,13,17,19,11,3,7,9,13,19,1,11,
%U A242120 17,3,9,11,17,1,3,13,7,11,13,17,11,17,7,9,13,19,7
%N A242120 a(n) = n-th prime modulo 20.
%H A242120 Vincenzo Librandi, <a href="/A242120/b242120.txt">Table of n, a(n) for n = 1..1000</a>
%F A242120 Sum_k={1..n} a(k) ~ 10*n. - _Amiram Eldar_, Dec 12 2024
%t A242120 Mod[Prime[Range[100]], 20]
%o A242120 (Magma) [p mod(20): p in PrimesUpTo(500)];
%o A242120 (Sage) [mod(p, 20) for p in primes(500)] # _Bruno Berselli_, May 05 2014
%Y A242120 Cf. similar sequences listed in A242119.
%K A242120 nonn,easy
%O A242120 1,1
%A A242120 _Vincenzo Librandi_, May 05 2014