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 A212109 #5 Dec 04 2016 19:46:29
%S A212109 0,1,15,69,203,467,935,1661,2770,4326,6476,9280,13025,17635,23475,
%T A212109 30614,39319,49557,61969,76227,93166,112525,134801,159969,189233,
%U A212109 221589,258185,299022,344875,395057,451641,512851,580999,655166,736374
%N A212109 Number of (w,x,y,z) with all terms in {1,...,n} and w*x-y*z<=n.
%C A212109 A212109(n)+A211060(n)=n^4. For a guide to related sequences, see A211795.
%t A212109 t = Compile[{{n, _Integer}}, Module[{s = 0},
%t A212109 (Do[If[w*x <= y*z + n, s = s + 1],
%t A212109 {w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
%t A212109 Map[t[#] &, Range[0, 40]] (* A212109 *)
%t A212109 (* _Peter J. C. Moses_, Apr 13 2012 *)
%Y A212109 Cf. A211795, A211060.
%K A212109 nonn
%O A212109 0,3
%A A212109 _Clark Kimberling_, May 07 2012