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 A308424 #8 Jun 16 2020 13:50:07
%S A308424 0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,1,0,1,2,1,1,2,1,1,0,1,2,1,
%T A308424 0,3,1,2,1,3,2,3,1,5,2,2,1,4,2,3,2,7,4,5,4,7,7,6,6,10,7,5,6,8,7,6,5,
%U A308424 12,5,5,4,9,7,5,6,11,6,4,5,9,8,5,5,13,5
%N A308424 Number of integer-sided triangles with perimeter n whose side lengths are nonsquarefree.
%H A308424 Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>
%F A308424 a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} sign(floor((i+k)/(n-i-k+1))) * (1 - mu(i)^2) * (1 - mu(k)^2) * (1 - mu(n-i-k)^2), where mu is the Möbius function (A008683).
%t A308424 Table[Sum[Sum[(1 - MoebiusMu[i]^2)*(1 - MoebiusMu[k]^2)*(1 - MoebiusMu[n - i - k]^2)*Sign[Floor[(i + k)/(n - i - k + 1)]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 100}]
%Y A308424 Cf. A008683, A308061.
%K A308424 nonn
%O A308424 1,25
%A A308424 _Wesley Ivan Hurt_, May 26 2019