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 A191562 #16 Sep 08 2022 08:45:57
%S A191562 1,1,1,1,7,1,7,1,1,19,7,1,7,7,28,1,7,1,7,1,28,49,7,1,7,49,1,49,7,19,7,
%T A191562 1,46,49,28,1,7,49,109,1,7,91,7,25,82,49,7,1,49,49,37,61,7,1,43,49,1,
%U A191562 49,7,1,7,49,28,1,37,37,7,157,136,49,7,1,7,49
%N A191562 a(n) = 7^n mod 3*n.
%H A191562 Vincenzo Librandi, <a href="/A191562/b191562.txt">Table of n, a(n) for n = 1..1000</a>
%t A191562 Table[PowerMod[7, n, 3 n], {n, 100}] (* _Vincenzo Librandi_, Jun 12 2016 *)
%o A191562 (Magma) [Modexp(7, n, 3*n): n in [1..100]]; // _Vincenzo Librandi_, Jun 12 2016
%o A191562 (PARI) a(n)=lift(Mod(7,3*n)^n) \\ _Charles R Greathouse IV_, Dec 27 2011
%Y A191562 Cf. A083528, A083529, A083530.
%K A191562 nonn,easy
%O A191562 1,5
%A A191562 _Vincenzo Librandi_, Jul 31 2011