OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
a(n) ~ 3^(n + 1/2) / sqrt(Pi*n). - Vaclav Kotesovec, Nov 06 2019
MAPLE
T:= proc(n, k) option remember;
if k=0 or k=2 or k=2*n then 1
elif k=1 then 0
else add(T(n-1, k-j), j=1..3)
fi
end:
seq( add(T(n, k), k=n..2*n), n=0..30); # G. C. Greubel, Nov 06 2019
MATHEMATICA
T[n_, k_]:= T[n, k]= If[k==0 || k==2 || k==2*n, 1, If[k==1, 0, Sum[T[n-1, k-j], {j, 3}]]]; Table[Sum[T[n, k], {k, n, 2*n}], {n, 0, 30}] (* G. C. Greubel, Nov 06 2019 *)
PROG
(Sage)
@CachedFunction
def T(n, k):
if (k==0 or k==2 or k==2*n): return 1
elif (k==1): return 0
else: return sum(T(n-1, k-j) for j in (1..3))
[sum(T(n, k) for k in (n..2*n)) for n in (0..30)] # G. C. Greubel, Nov 06 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved