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 A070098 #23 Sep 08 2022 08:45:05 %S A070098 0,0,1,0,1,1,1,1,2,2,2,2,3,2,3,3,4,3,4,4,4,4,5,4,5,5,6,5,6,6,6,6,7,7, %T A070098 7,7,8,7,8,8,8,8,9,9,9,9,10,9,10,10,11,10,11,11,11,11,12,12,12,12,13, %U A070098 12,13,13,13,13,14,14,14,14,15,14,15,15,16,15 %N A070098 Number of integer triangles with perimeter n which are acute and isosceles. %C A070098 Equivalently, the number of obtuse isosceles integer triangles with base n. - _Charlie Marion_, Jun 18 2019 %H A070098 Marius A. Burtea, <a href="/A070098/b070098.txt">Table of n, a(n) for n = 1..10000</a> %H A070098 Reinhard Zumkeller, <a href="/A070080/a070080.txt">Integer-sided triangles</a> %F A070098 a(n) = A070093(n)-A024154(n); a(n) = A059169(n)-A070106(n). %F A070098 a(n) = floor(n/2) - floor(n/(2 + sqrt(2))) - ((n + 1) mod 2). - _David Pasino_, Jun 27 2016 %F A070098 a(n) = A004526(n-1) - A183138(n). - _R. J. Mathar_, May 22 2019 %e A070098 For n=9 there are A005044(9)=3 integer triangles: [1,4,4], [2,3,4] and [3,3,3]; both isosceles are also acute. %o A070098 (Magma) [Floor(k/2)-Floor(k/(2 + Sqrt(2)))-((k + 1) mod 2): k in [1..76]]; // _Marius A. Burtea_, Jun 21 2019 %Y A070098 Cf. A070080, A070081, A070082, A059169, A070099, A070100, A070124. %K A070098 nonn %O A070098 1,9 %A A070098 _Reinhard Zumkeller_, May 05 2002