A027030 a(n) = T(n,2n-6), T given by A027023.

1, 1, 5, 17, 57, 189, 613, 1949, 6097, 18825, 57525, 174353, 525049, 1573077, 4693909, 13960805, 41415089, 122603341, 362343053, 1069436317, 3152995209, 9287942097, 27341397469, 80443393889, 236581555233, 695561538977

Offset

3,3

Links

G. C. Greubel, Table of n, a(n) for n = 3..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-6), n=3..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-6], {n, 3, 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-6) for n in (3..30)] # G. C. Greubel, Nov 04 2019

Crossrefs

Sequence in context: A145371 A347750 A112044 * A033538 A027093 A027032

Adjacent sequences: A027027 A027028 A027029 * A027031 A027032 A027033

Keyword

nonn

Author

Clark Kimberling

Status

approved