A026134 a(n) = Sum_{k=1..n} T(k, k-1), where T is the array in A026120.

1, 2, 6, 16, 44, 120, 329, 904, 2493, 6898, 19151, 53340, 149019, 417522, 1172979, 3303696, 9326931, 26390070, 74824584, 212565864, 604972998, 1724739940, 4925066567, 14085122376, 40339596755, 115688495806, 332203673142, 955090832416, 2749055259956, 7921280088744

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

• Ricardo Gómez Aíza, Trees with flowers: A catalog of integer partition and integer composition trees with their asymptotic analysis, arXiv:2402.16111 [math.CO], 2024. See p. 21.

Crossrefs

T(n, n+2), where T is given by A026148, T(n, n-2), where T is the array defined in A026105 and T(n, n+1), where T is given by A026323.

First differences of A005322.

Cf. A026123.

Formula

G.f.: z(1-z)M^3, with M the g.f. of the Motzkin numbers (A001006).

Extensions

a(25) corrected and more terms from Sean A. Irvine, Sep 17 2019