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 A164831 #13 Jan 18 2024 07:46:36 %S A164831 0,1,3,4,7,12,12,19,22,29,25,40,29,48,59,85,42,83,53,93,99,96,64,175, %T A164831 144,113,159,161,97,235,100,297,187,165,231,274,111,200,224,386,156, %U A164831 398,149,303,425,248,152,733,450,513,332,359,181,572,448,648,384,361,221,786 %N A164831 a(n) is the number of values taken by cos(2*Pi/k) mod n for all k in 1..n-1. %C A164831 See A164823 for explanatory comment and the definition of "cos(x) mod j". %H A164831 Christopher Hunt Gribble, <a href="/A164831/b164831.txt">Table of n, a(n) for n = 1..1000</a>. %Y A164831 Cf. A164822, A164823, A164846, A165252. %K A164831 nonn %O A164831 1,3 %A A164831 _Christopher Hunt Gribble_, Aug 27 2009 %E A164831 Edited by _N. J. A. Sloane_, Sep 01 2009 %E A164831 Sequence corrected by _Christopher Hunt Gribble_, Sep 10 2009