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 A320311 #5 Oct 10 2018 20:06:47 %S A320311 0,0,0,1,0,2,0,3,0,5,0,6,1,6,0,8,2,9,2,10,0,15,1,14,1,15,3,15,2,17,4, %T A320311 19,3,21,1,21,4,26,3,25,4,24,4,27,6,29,5,31,5,30,4,36,4,37,6,34,6,41, %U A320311 8,36,8,43,4,42,5,44,10,44,9,45,9,45,10,48 %N A320311 Number of ways to write n as the sum of 4 positive integers a, b, c, d such that 1 - a/c = (1 - b/d)^2. %o A320311 (PARI) m=74;v=vector(m);for(a=1,m,for(b=1,m,for(c=1,m,for(d=1,m,n=a+b+c+d;if(n<=m,if(1-a/c==(1-b/d)^2,v[n]++))))));v %Y A320311 Cf. A026810, A319853, A319854, A320312, A320313. %K A320311 nonn %O A320311 1,6 %A A320311 _Hugo Pfoertner_ and _Rainer Rosenthal_ Oct 10 2018