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 A308303 #6 Jun 18 2020 13:55:37
%S A308303 0,0,0,0,1,1,1,1,2,2,2,3,4,4,4,5,6,7,6,8,9,10,9,12,12,14,12,16,16,19,
%T A308303 16,21,20,24,20,27,25,30,25,33,30,37,30,40,36,44,36,48,42,52,42,56,49,
%U A308303 61,49,65,56,70,56,75,64,80,64,85,72,91,72,96,81,102
%N A308303 Number of integer-sided triangles with perimeter n and at least one even side length.
%H A308303 Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>
%F A308303 a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} sign(floor((i+k)/(n-i-k+1))) * (1 - (i mod 2) * (k mod 2) * ((n-i-k) mod 2)).
%F A308303 a(n) = A005044(n) - A308065(n).
%t A308303 Table[Sum[Sum[(1 - Mod[i, 2] Mod[k, 2] Mod[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 A308303 Cf. A005044, A308065.
%K A308303 nonn
%O A308303 1,9
%A A308303 _Wesley Ivan Hurt_, May 19 2019