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 A293665 #6 Oct 16 2017 17:20:51
%S A293665 1,-1,0,-1,0,-1,1,-2,0,-2,2,-3,1,-2,2,-6,2,-3,7,-8,2,-12,12,-13,0,-3,
%T A293665 4,-12,17,-18,19,-20,-19,-13,34,-71,54,-55,8,-67,73,-74,79,-80,-72,
%U A293665 -154,238,-239,39,-119,163,-237,97,-98,310,-402,-22,-297,336,-337,271,-272,20,-659,369,-738
%N A293665 a(0) = 1; a(n) = -Sum_{d|n} a(n-d).
%H A293665 Ilya Gutkovskiy, <a href="/A293665/a293665.pdf">Extended graphical example</a>
%F A293665 a(p) = -a(p-1) - 1, for p is a prime.
%t A293665 a[n_] := a[n] = -Sum[a[n - d], {d, Divisors[n]}]; a[0] = 1; Table[a[n], {n, 0, 65}]
%Y A293665 Cf. A067951, A281487, A281488.
%K A293665 sign
%O A293665 0,8
%A A293665 _Ilya Gutkovskiy_, Oct 14 2017