A026753 a(n) = T(n, floor(n/2)), T given by A026747.

1, 1, 3, 4, 11, 17, 44, 74, 184, 327, 790, 1461, 3452, 6584, 15278, 29879, 68290, 136391, 307696, 625731, 1395696, 2883357, 6367199, 13338421, 29193025, 61920497, 134442102, 288368511, 621609060, 1346873365, 2884432810

Offset

0,3

Links

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

Maple

A026747 := proc(n, k) option remember;
   if k=0 or k = n then 1;
   elif type(n, 'even') and 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) ;
   end if ;
end proc:
seq(A026747(n, floor(n/2)), n=0..30); # G. C. Greubel, Oct 29 2019

Mathematica

T[n_, k_]:= T[n, k]= If[k==0 || k==n, 1, If[EvenQ[n] && 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, Oct 29 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): 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 29 2019

Crossrefs

Cf. A026747, A026748, A026749, A026750, A026751, A026752, A026754, A026755, A026756, A026757.

Sequence in context: A143680 A058569 A231882 * A027222 A026380 A030225

Adjacent sequences: A026750 A026751 A026752 * A026754 A026755 A026756

Keyword

nonn

Author

Clark Kimberling

Status

approved