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 A212147 (A212146(n)-1)/2. 3
 0, 1, 3, 6, 11, 18, 29, 45, 70, 108, 170, 270, 439, 726, 1227, 2108, 3685, 6523, 11687, 21129, 38513, 70649, 130347, 241610, 449735, 840134, 1574537, 2959350, 5576730, 10533846, 19940812, 37823859, 71878024, 136827410, 260884686, 498167480, 952607343 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A212146(n) is the number of subsets of {1,...,n} having mean=median. LINKS Hiroaki Yamanouchi, Table of n, a(n) for n = 1..100 MATHEMATICA t[n_, k_] := t[n, k] = Count[Map[Median[#] == Mean[#] &, Subsets[Range[n], {k}]], True] Flatten[Table[t[n, k], {n, 1, 12}, {k, 1, n}]]  (* A212139 *) TableForm[Table[t[n, k], {n, 1, 12}, {k, 1, n}]] s[n_] := Sum[t[n, k], {k, 1, n}] Table[s[n], {n, 1, 22}]   (* A212146 *) (% - 1)/2                 (* A212147 *) (* Peter J. C. Moses, May 01 2012 *) Cf. A212138. CROSSREFS Sequence in context: A281689 A026905 A286272 * A066778 A265075 A147079 Adjacent sequences:  A212144 A212145 A212146 * A212148 A212149 A212150 KEYWORD nonn AUTHOR Clark Kimberling, May 06 2012 EXTENSIONS a(23)-a(37) from Hiroaki Yamanouchi, Oct 03 2014 STATUS approved

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