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 A308218 #6 Jun 18 2020 13:45:41
%S A308218 0,0,0,0,0,0,2,0,3,0,7,0,9,9,15,11,18,18,32,21,51,30,64,41,79,62,95,
%T A308218 77,113,93,151,124,186,144,221,177,249,225,289,253,333,310,411,343,
%U A308218 479,390,534,456,593,527,674,605,756,667,859,733,954,826,1049,936
%N A308218 Take the integer-sided obtuse triangles with perimeter n and sides a, b and c such that a <= b <= c. a(n) is the sum of all the b's.
%H A308218 Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>
%F A308218 a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} (1-sign(floor((i^2 + k^2)/(n-i-k)^2))) * sign(floor((i+k)/(n-i-k+1))) i.
%t A308218 Table[Sum[Sum[i (1 - Sign[Floor[(i^2 + k^2)/(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 A308218 Cf. A308216.
%K A308218 nonn
%O A308218 1,7
%A A308218 _Wesley Ivan Hurt_, May 15 2019