A026744 a(n) = Sum_{j=0..floor(n/2)} T(n,j), T given by A026736.

1, 1, 3, 4, 12, 18, 51, 81, 220, 361, 952, 1595, 4118, 6999, 17787, 30548, 76696, 132766, 330148, 575054, 1418946, 2483812, 6089912, 10703456, 26104178, 46034722, 111769554, 197665364, 478085534, 847542518, 2043167075

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Mathematica

T[n_, k_]:= T[n, k] = If[k==0 || k==n, 1, If[EvenQ[n] && k==(n-2)/2, T[n-1, k-1] + T[n-2, k-1] + T[n-1, k], T[n-1, k-1] + T[n-1, k]]];
Table[Sum[T[n, j], {j, 0, Floor[n/2]}], {n, 0, 35}] (* G. C. Greubel, Jul 22 2019 *)

Prog

(Sage)
@CachedFunction
def T(n, k):
    if (k==0 or k==n): return 1
    elif (mod(n, 2)==0 and k==(n-2)/2): return T(n-1, k-1) + T(n-2, k-1) + T(n-1, k)
    else: return T(n-1, k-1) + T(n-1, k)
[sum(T(n, j) for j in (0..floor(n/2))) for n in (0..35)] # G. C. Greubel, Jul 22 2019

Crossrefs

Cf. A026736.

Sequence in context: A064140 A064139 A306176 * A347257 A123765 A124817

Adjacent sequences: A026741 A026742 A026743 * A026745 A026746 A026747

Keyword

nonn

Author

Clark Kimberling

Status

approved