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 A212147 #14 Aug 04 2018 04:11:22
%S A212147 0,1,3,6,11,18,29,45,70,108,170,270,439,726,1227,2108,3685,6523,11687,
%T A212147 21129,38513,70649,130347,241610,449735,840134,1574537,2959350,
%U A212147 5576730,10533846,19940812,37823859,71878024,136827410,260884686,498167480,952607343
%N A212147 a(n) = (A212146(n)-1)/2.
%C A212147 A212146(n) is the number of subsets of {1,...,n} having mean=median.
%H A212147 Hiroaki Yamanouchi, <a href="/A212147/b212147.txt">Table of n, a(n) for n = 1..100</a>
%t A212147 t[n_, k_] := t[n, k] = Count[Map[Median[#] == Mean[#] &, Subsets[Range[n], {k}]], True]
%t A212147 Flatten[Table[t[n, k], {n, 1, 12}, {k, 1, n}]] (* A212139 *)
%t A212147 TableForm[Table[t[n, k], {n, 1, 12}, {k, 1, n}]]
%t A212147 s[n_] := Sum[t[n, k], {k, 1, n}]
%t A212147 Table[s[n], {n, 1, 22}] (* A212146 *)
%t A212147 (% - 1)/2 (* A212147 *)
%t A212147 (* _Peter J. C. Moses_, May 01 2012 *)
%Y A212147 Cf. A212138.
%K A212147 nonn
%O A212147 1,3
%A A212147 _Clark Kimberling_, May 06 2012
%E A212147 a(23)-a(37) from _Hiroaki Yamanouchi_, Oct 03 2014