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A208976 Row sums of the triangle in A208101. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) = A050168(n+1) - 1.

Number of Dyck (n+1)-paths that are symmetric after deleting all leading hills. - David Scambler, Aug 23 2012

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = A001405(n) + A001405(n+1) - 1.

MATHEMATICA

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}];

Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 03 2018, from A208101 *)

PROG

(Haskell)

a208976 n = a208976_list !! n

a208976_list = map (subtract 1) $ tail a050168_list

CROSSREFS

Sequence in context: A036621 A001383 A217733 * A278554 A335473 A224959

Adjacent sequences: A208973 A208974 A208975 * A208977 A208978 A208979

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 04 2012

STATUS

approved

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Last modified December 8 07:08 EST 2022. Contains 358673 sequences. (Running on oeis4.)