OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: A(x) where (4*x^6-13*x^4-18*x^3+41*x^2+22*x-5)*A(x)^3+(4-3*x^2)*A(x)+1=0. - Mark van Hoeij, Apr 17 2013
MAPLE
P := (4*x^6-13*x^4-18*x^3+41*x^2+22*x-5)*A^3+(4-3*x^2)*A+1;
series(RootOf(P, A), x=0, 30); # Mark van Hoeij, Apr 17 2013
# second Maple program:
b:= proc(p) b(p):= `if`(p=[0$2], 1, `if`(min(p[])<0, 0,
add(b(p-l), l=[[0, 1], [0, 2], [1, 0], [2, 2]])))
end:
a:= n-> b([n$2]):
seq(a(n), n=0..30); # Alois P. Heinz, Aug 18 2014
MATHEMATICA
b[p_List] := b[p] = If[p == {0, 0}, 1, If[Min[p] < 0, 0, Sum[b[p-l], {l, {{0, 1}, {0, 2}, {1, 0}, {2, 2}}}]]]; a[n_] := b[{n, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, May 27 2015, after Alois P. Heinz *)
PROG
(PARI) /* same as in A092566 but use */
steps=[[0, 1], [0, 2], [1, 0], [2, 2]];
/* Joerg Arndt, Jun 30 2011 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Jun 30 2011
STATUS
approved