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 A070102 #5 Mar 30 2012 18:50:20 %S A070102 0,0,0,0,0,0,1,0,1,0,2,0,2,1,3,2,3,2,5,3,6,2,8,5,9,5,9,6,11,6,14,9,14, %T A070102 9,17,11,19,12,19,15,23,13,27,18,26,16,32,20,33,21,34,26,40,23,42,29, %U A070102 42,29,50,32,53,35,48,41,58,37,64,45,60,42,71 %N A070102 Number of obtuse integer triangles with perimeter n and relatively prime side lengths. %C A070102 a(n) = A051493(n) - A070094(n) - A070109(n). %H A070102 R. Zumkeller, <a href="/A070080/a070080.txt">Integer-sided triangles</a> %e A070102 For n=9 there are A005044(9)=3 integer triangles: [1,4,4], [2,3,4] and [3,3,3]; only one of them is obtuse: 2^2+3^2<16=4^2 and GCD(2,3,4)=1, therefore a(9)=1. %Y A070102 Cf. A070080, A070081, A070082, A070101, A051493, A070104, A070107, A070084, A070128. %K A070102 nonn %O A070102 1,11 %A A070102 _Reinhard Zumkeller_, May 05 2002