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A212140 Number of k-element subsets S of {1,...,n} such that mean(S) is not equal to median(S). 3
0, 0, 0, 2, 8, 26, 68, 164, 370, 806, 1706, 3554, 7312, 14930, 30312, 61318, 123700, 249096, 500912, 1006316 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Row sums of the triangular array at A212148.

LINKS

Table of n, a(n) for n=1..20.

MATHEMATICA

t[n_, k_] := t[n, k] = Count[Map[Median[#] == Mean[#] &, Subsets[Range[n], {k}]], False]

Flatten[Table[t[n, k], {n, 1, 12}, {k, 1, n}]]

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, 20}] (* A212140 *)

%/2                     (* A212149 *)

(* Peter J. C. Moses, May 01 2012 *)

CROSSREFS

Cf. A212148, A212149.

Sequence in context: A211885 A101696 A155861 * A136594 A268502 A167826

Adjacent sequences:  A212137 A212138 A212139 * A212141 A212142 A212143

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 06 2012

STATUS

approved

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Last modified June 17 17:33 EDT 2021. Contains 345085 sequences. (Running on oeis4.)