OFFSET
1,5
COMMENTS
See Kitaev et al. for precise definition.
LINKS
S. Kitaev, P. Salimov, C. Severs and H. Ulfarsson, Restricted non-separable planar maps and some pattern avoiding permutations, preprint 2012.
S. Kitaev, P. Salimov, C. Severs and H. Ulfarsson, Restricted non-separable planar maps and some pattern avoiding permutations, Discrete Applied Mathematics, Volume 161, Issues 16-17, November 2013, Pages 2514-2526. See B_3(x).
FORMULA
Kitaev et al. give a functional equation that is satisfied by the g.f.
PROG
(PARI)
a(n) = {
B = x + O(x^(n+1));
for (i=1, n,
B = x + B*(B-x) + (B-x)^2 + (B-x-x*B^2)*(B-x) + x*(3*B-2*x-x*B^2)^2; );
polcoeff(B, n, x);
} \\ Michel Marcus, Feb 07 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 01 2013
EXTENSIONS
More terms from Michel Marcus, Feb 07 2013
STATUS
approved