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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
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OFFSET
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1,3
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COMMENTS
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A212146(n) is the number of subsets of {1,...,n} having mean=median.
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LINKS
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Hiroaki Yamanouchi, Table of n, a(n) for n = 1..100
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MATHEMATICA
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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 *)
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CROSSREFS
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Cf. A212138.
Sequence in context: A281689 A026905 A286272 * A066778 A265075 A147079
Adjacent sequences: A212144 A212145 A212146 * A212148 A212149 A212150
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KEYWORD
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nonn
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AUTHOR
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Clark Kimberling, May 06 2012
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EXTENSIONS
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a(23)-a(37) from Hiroaki Yamanouchi, Oct 03 2014
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STATUS
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approved
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