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 A340781 #17 Jun 27 2021 04:50:36
%S A340781 0,2,4,5,8,7,12,9,2,18,29,7,24,9,37,37,32,41,5,38,47,5,49,6,96,50,1,
%T A340781 54,3,67,120,55,64,52,68,59,59,148,61,61,80,48,84,172,88,142,130,188,
%U A340781 96,196,67,102,38,67,67,67,112,71,232,118,34,268,248,126,256,276
%N A340781 a(n) = (n - 1)*prime(n + 1) mod prime(n).
%H A340781 Stefano Spezia, <a href="/A340781/b340781.txt">Table of n, a(n) for n = 1..10000</a>
%F A340781 a(n) = A306192(n) mod A000040(n).
%t A340781 Table[Mod[(n-1)Prime[n+1],Prime[n]],{n,66}]
%o A340781 (PARI) a(n) = ((n-1)*prime(n+1)) % prime(n); \\ _Michel Marcus_, Jan 21 2021
%Y A340781 Cf. A000040, A033286, A306192, A340128, A340649.
%K A340781 nonn,look
%O A340781 1,2
%A A340781 _Stefano Spezia_, Jan 21 2021