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 A382066 #19 Mar 31 2025 21:19:51
%S A382066 1,8,151,8083,70568,8910416,39392803,7701058213,2325990648824,
%T A382066 43563061207573,19999898090377928,2566793589644124992,
%U A382066 10627327735475477203,2179055220073884519235,630486036620986837882904,646895254841829205782412249,5802709167332592724735012664
%N A382066 a(n) = Sum_{k=1..prime(n)-1} (-k/prime(n)) * 3^(k-1) / 2, where (p/q) is the Legendre symbol of p and q.
%C A382066 All terms are integers since Sum_{k=1..p-1} (-k/p) * 3^(k-1) is even for any odd prime p.
%H A382066 Steven Lu, <a href="/A382066/b382066.txt">Table of n, a(n) for n = 2..316</a>
%t A382066 Table[Sum[KroneckerSymbol[-i, q] 3^(i - 1), {i, q - 1}], {q, Prime /@ Range[2, 18]}]/2
%K A382066 nonn
%O A382066 2,2
%A A382066 _Steven Lu_, Mar 14 2025