A027032 a(n) = T(n,2n-8), T given by A027023.

1, 1, 5, 17, 57, 193, 649, 2161, 7113, 23137, 74417, 236913, 747401, 2339137, 7270189, 22460801, 69031105, 211206529, 643684485, 1955082321, 5920720729, 17884040961, 53898818389, 162120056257, 486791503521, 1459448379329

Offset: 4

Author

Clark Kimberling

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 4..750

Programs

Maple

T:= proc(n, k) option remember;
      if k<3 or k=2*n then 1
    else add(T(n-1, k-j), j=1..3)
      fi
    end:
seq(T(n,2*n-8), n=4..30); # G. C. Greubel, Nov 05 2019

Mathematica

T[n_, k_]:= T[n, k]= If[n<0, 0, If[k<3 || k==2*n, 1, Sum[T[n-1, k-j], {j, 3}]]]; Table[T[n, 2*n-8], {n,4,30}] (* G. C. Greubel, Nov 05 2019 *)

Sage

@CachedFunction
def T(n, k):
    if (k<3 or k==2*n): return 1
    else: return sum(T(n-1, k-j) for j in (1..3))
[T(n, 2*n-8) for n in (4..30)] # G. C. Greubel, Nov 05 2019