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A208976
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Row sums of the triangle in A208101.
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3
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1, 2, 4, 8, 15, 29, 54, 104, 195, 377, 713, 1385, 2639, 5147, 9866, 19304, 37179, 72929, 140997, 277133, 537471, 1058147, 2057509, 4056233, 7904455, 15600899, 30458899, 60174899, 117675359, 232676279, 455657714, 901620584, 1767883499, 3500409329, 6871173869
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OFFSET
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0,2
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COMMENTS
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Number of Dyck (n+1)-paths that are symmetric after deleting all leading hills. - David Scambler, Aug 23 2012
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LINKS
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FORMULA
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MATHEMATICA
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T[_, 0] = 1; T[n_, 1] := n; T[n_, n_] := T[n - 1, n - 2]; T[n_, k_] /; 1 < k < n := T[n, k] = T[n - 1, k] + T[n - 1, k - 2];
a[n_] := Sum[T[n, k], {k, 0, n}];
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PROG
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(Haskell)
a208976 n = a208976_list !! n
a208976_list = map (subtract 1) $ tail a050168_list
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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