A027033 a(n) = T(n,2n-9), T given by A027023.

1, 3, 9, 31, 105, 355, 1197, 4011, 13329, 43883, 143105, 462391, 1481229, 4707743, 14856441, 46585671, 145253757, 450624055, 1391743825, 4281348119, 13124142489, 40105164499, 122213161617, 371496978671, 1126750503081

Offset

5,2

Links

G. C. Greubel, Table of n, a(n) for n = 5..750

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-9), 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-9], {n, 5, 30}] (* G. C. Greubel, Nov 05 2019 *)

Prog

(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-9) for n in (5..30)] # G. C. Greubel, Nov 05 2019

Crossrefs

Sequence in context: A148963 A027031 A027094 * A027096 A221440 A289599

Adjacent sequences: A027030 A027031 A027032 * A027034 A027035 A027036

Keyword

nonn

Author

Clark Kimberling

Status

approved