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 A309149 #23 Jul 24 2019 02:53:31
%S A309149 0,3,9,14,22,33,29,44,56,65,50,108,53,101,141,97,64,150,73,216,184,
%T A309149 119,81,274,138,141,182,263,101,378,90,222,270,183,375,419,102,185,
%U A309149 319,479,121,486,115,394,520,187,118,565,227,362
%N A309149 Number of solutions of the Diophantine equation 1/n + 1/x = 1/y + 1/z, where n >= 1, x >= n, y > n and z >= y.
%e A309149 n=2: 1/2 + 1/6 = 1/3 + 1/3, 1/2 + 1/12 = 1/3 + 1/4, 1/2 + 1/30 = 1/3 + 1/5.
%t A309149 a[n_]:=Length@Solve[1/(n)+1/(x)==1/y+1/z&&x>=n&&z>=y&&y>n,{x,y,z},Integers];
%t A309149 Array[a,50]
%Y A309149 Cf. A309150, A063647, A018892.
%K A309149 nonn
%O A309149 1,2
%A A309149 _S. Nazardonyavi_, Jul 14 2019