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 A212138 Triangular array:  T(n,k) is the number of k-element subsets S of {1,...,n} whose average is in S. 3
 1, 2, 0, 3, 0, 1, 4, 0, 2, 0, 5, 0, 4, 0, 1, 6, 0, 6, 2, 2, 0, 7, 0, 9, 4, 5, 0, 1, 8, 0, 12, 8, 10, 2, 2, 0, 9, 0, 16, 14, 18, 8, 6, 0, 1, 10, 0, 20, 22, 32, 20, 14, 4, 2, 0, 11, 0, 25, 32, 52, 42, 34, 14, 7, 0, 1, 12, 0, 30, 46, 80, 80, 72, 42, 22, 4, 2, 0, 13, 0, 36, 62, 119, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE First 7 rows: 1 2...0 3...0...1 4...0...2...0 5...0...4...0...1 6...0...6...2...2...0 7...0...9...4...5...0...1 T(5,3) counts these subsets: {1,2,3}, 1,3,5}, {2,3,4}, {3,4,5}. MATHEMATICA t[n_, k_] := Length[Flatten[Map[Apply[Intersection, #] &,     Select[Map[{#, {Mean[#]}} &, Subsets[Range[n], {k}]], IntegerQ[Last[Last[#]]] &]]]] Flatten[Table[t[n, k], {n, 1, 12}, {k, 1, n}]] TableForm[Table[t[n, k], {n, 1, 12}, {k, 1, n}]] (* Peter J. C. Moses, May 01 2012 *) CROSSREFS Cf. A061865. Sequence in context: A088673 A236138 A035614 * A133735 A238801 A095704 Adjacent sequences:  A212135 A212136 A212137 * A212139 A212140 A212141 KEYWORD nonn,tabl AUTHOR Clark Kimberling, May 06 2012 STATUS approved

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Last modified February 19 09:55 EST 2020. Contains 332041 sequences. (Running on oeis4.)