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 A212103 #7 Dec 04 2016 19:46:29
%S A212103 0,1,2,3,10,11,30,31,38,39,52,53,84,85,86,117,124,125,144,145,200,225,
%T A212103 226,227,282,283,284,285,334,335,420,421,428,435,436,491,546,547,548,
%U A212103 555,634,635,726,727,758,837,838,839,936,937,956,957,970,971
%N A212103 Number of (w,x,y,z) with all terms in {1,...,n} and w = harmonic mean of {x,y,z}.
%C A212103 Also, the number of (w,x,y,z) with all terms in {1,...,n} and H(w,x,y)=H(w,x,y,z) where H denotes harmonic mean. For a guide to related sequences, see A211795.
%e A212103 a(4) counts these: (1,1,1,1), (2,1,4,4), (2,2,2,2), (2,4,1,4), (2,4,4,1), (3,2,4,4), (3,3,3,3), (3,4,2,4), (3,4,4,2), (4,4,4,4); e.g., (3,2,4,4) is included because it satisfies 3/w=1/x+1/y+1/z.
%t A212103 t = Compile[{{n, _Integer}}, Module[{s = 0},
%t A212103 (Do[If[w*(y*z + z*x + x*y) == 3 x*y*z, s = s + 1],
%t A212103 {w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
%t A212103 Map[t[#] &, Range[0, 60]] (* A212103 *)
%t A212103 (* _Peter J. C. Moses_, Apr 13 2012 *)
%Y A212103 Cf. A211795.
%K A212103 nonn
%O A212103 0,3
%A A212103 _Clark Kimberling_, May 03 2012