A027034 a(n) = T(n,2n-10), T given by A027023.

1, 1, 5, 17, 57, 193, 653, 2205, 7417, 24805, 82373, 271437, 887377, 2878509, 9268429, 29636981, 94163769, 297435285, 934521973, 2922073641, 9096981049, 28209178729, 87163760797, 268462020889, 824451264113, 2525238433145

Offset: 5

Author

Clark Kimberling

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 5..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-10), n=5..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-10], {n,5,30}] (* 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-10) for n in (5..30)] # G. C. Greubel, Nov 05 2019