OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
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(add(T(n, k), k=n+1..2*n), n=1..30); # G. C. Greubel, Nov 04 2019
MATHEMATICA
T[n_, k_]:= T[n, k]= If[k<3 || k==2*n, 1, Sum[T[n-1, k-j], {j, 3}]]; Table[Sum[T[n, k], {k, n+1, 2*n}], {n, 30}] (* G. C. Greubel, Nov 04 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))
[sum(T(n, k) for k in (n+1..2*n)) for n in (1..30)] # G. C. Greubel, Nov 04 2019
(Magma) function T(n, k)
if k lt 3 or k eq 2*n then return 1;
else return (&+[T(n-1, k-j): j in [1..3]]);
end if; return T; end function;
[(&+[T(n, k): k in [n+1..2*n]]): n in [1..15]]; // G. C. Greubel, Nov 20 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset changed by G. C. Greubel, Nov 04 2019
STATUS
approved