A026786 a(n) = T(n, floor(n/2)), T given by A026780.

1, 1, 3, 5, 12, 24, 53, 117, 246, 580, 1178, 2916, 5768, 14834, 28731, 76221, 145108, 395048, 741392, 2063104, 3825418, 10847078, 19907156, 57373672, 104370554, 305110106, 550816506, 1630489090, 2924018194, 8751851866

Offset

0,3

Links

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

Maple

T:= proc(n, k) option remember;
    if n<0 then 0;
    elif k=0 or k =n then 1;
    elif k <= n/2 then
        procname(n-1, k-1)+procname(n-2, k-1)+procname(n-1, k) ;
    else
        procname(n-1, k-1)+procname(n-1, k) ;
    fi ;
end proc:
seq(T(n, floor(n/2)), n=0..30); # G. C. Greubel, Nov 02 2019

Mathematica

T[n_, k_]:= T[n, k]= If[n<0, 0, If[k==0 || k==n, 1, If[k<=n/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[T[n, Floor[n/2]], {n, 0, 30}] (* G. C. Greubel, Nov 02 2019 *)

Prog

(Sage)
@CachedFunction
def T(n, k):
    if (n<0): return 0
    elif (k==0 or k==n): return 1
    elif (k<=n/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)
[T(n, floor(n/2)) for n in (0..30)] # G. C. Greubel, Nov 02 2019

Crossrefs

Cf. A026780, A026781, A026782, A026783, A026784, A026785, A026787, A026788, A026789, A026790.

Sequence in context: A036657 A047761 A349055 * A027246 A185087 A090345

Adjacent sequences: A026783 A026784 A026785 * A026787 A026788 A026789

Keyword

nonn

Author

Clark Kimberling

Status

approved