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 A308157 #7 Jun 16 2020 14:27:48
%S A308157 0,0,0,0,0,0,7,0,9,0,22,0,26,28,45,32,51,54,95,60,147,88,184,120,225,
%T A308157 182,270,224,319,270,434,352,528,408,630,504,703,646,819,720,943,882,
%U A308157 1161,968,1350,1104,1504,1296,1666,1500,1887,1716,2120,1890,2420
%N A308157 Sum of the perimeters of all integer-sided obtuse triangles with perimeter n.
%H A308157 Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>
%F A308157 a(n) = n * A070101(n).
%F A308157 a(n) = 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))).
%t A308157 Table[n*Sum[Sum[ (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 A308157 Cf. A070101.
%K A308157 nonn
%O A308157 1,7
%A A308157 _Wesley Ivan Hurt_, May 14 2019