OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
José L. Ramírez, The Pascal Rhombus and the Generalized Grand Motzkin Paths, arXiv:1511.04577 [math.CO], 2015.
FORMULA
Conjecture: +(n-2)*(n-3)*(n+3)*a(n) -n*(2*n-1)*(n-2)*a(n-1) -(n-1)*(5*n^2-10*n+18)*a(n-2) +n*(2*n-3)*(n-2)*a(n-3) +n*(n+1)*(n-5)*a(n-4)=0. - R. J. Mathar, Jul 23 2017
MAPLE
T:= proc(n, k) option remember; `if`(min(n, k)<0, 0,
`if`(k=0, 1, T(n-1, k)+T(n-1, k-1)+T(n-1, k-2)+T(n-2, k-2)))
end:
a:= n-> T(n, n-3):
seq(a(n), n=0..30); # Alois P. Heinz, Jan 24 2016
MATHEMATICA
T[n_, k_] := T[n, k] = If[Min[n, k]<0, 0, If[k == 0, 1, T[n-1, k] + T[n-1, k-1] + T[n-1, k-2] + T[n-2, k-2]]];
a[n_] := T[n, n-3];
Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Jun 23 2017, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 22 2016
EXTENSIONS
More terms from Alois P. Heinz, Jan 24 2016
STATUS
approved