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 A306991 #26 May 23 2019 08:39:29 %S A306991 1,1,1,2,2,3,2,2,3,3,5,4,3,6,4,4,5,4,8,6,9,6,6,4,8,11,8,10,6,9,9,8,14, %T A306991 6,15,10,11,10,8,12,10,12,18,9,12,12,20,14,8,21,15,12,16,10,23,16,21, %U A306991 12,12,16,18,26,18,20,12,16,18,20,29,12,21,30 %N A306991 Number of primitive Heronian isosceles triangles with perimeter A308222(n). %C A306991 Records occur at indices of 1, 4, 6, 11, 14, 19, 21, 26, 33, 35, ... corresponding to perimeters of 16, 50, 98, 242, 338, 578, 722, 1058, 1682, 1922, ... %e A306991 For n = 6, the a(6) = 3 primitive Heronian isosceles triangles with perimeter A308222(6) = 98 have side lengths (24,37,37), (25,25,48), and (29,29,40), and areas of 420, 168, and 420 respectively. %Y A306991 Cf. A298614, A305717, A308222. %K A306991 nonn %O A306991 1,4 %A A306991 _Peter Kagey_, May 18 2019