A026764 a(n) = T(n, floor(n/2)), T given by A026758.

1, 1, 2, 4, 7, 16, 27, 66, 109, 279, 453, 1201, 1922, 5242, 8284, 23133, 36155, 103015, 159435, 462269, 709246, 2088146, 3178992, 9487405, 14343567, 43328580, 65099245, 198798447, 297015765, 915950385, 1361584755, 4236322720

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 type(n, 'odd') and k <= (n-1)/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) ;
   end if ;
end proc;
seq(T(n, floor(n/2)), n=0..30); # G. C. Greubel, Oct 31 2019

Mathematica

T[n_, k_]:= T[n, k]= If[n<0, 0, If[k==0 || k==n, 1, If[OddQ[n] && k<=(n - 1)/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, Oct 31 2019 *)

Prog

(Sage)
@CachedFunction
def T(n, k):
    if (n<0): return 0
    elif (k==0 or k==n): return 1
    elif (mod(n, 2)==1 and k<=(n-1)/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, Oct 31 2019

Crossrefs

Cf. A026758, A026759, A026760, A026761, A026762, A026763, A026765, A026766, A026767, A026768.

Sequence in context: A338647 A361334 A026731 * A027230 A217929 A320465

Adjacent sequences: A026761 A026762 A026763 * A026765 A026766 A026767

Keyword

nonn

Author

Clark Kimberling

Status

approved