A060898 Number of walks of length n on square lattice, starting at origin, staying in first, second and third quadrants.

1, 4, 14, 54, 200, 776, 2940, 11466, 43980, 172170, 665544, 2612764, 10154144, 39949000, 155864280, 614260062, 2403739140, 9486263092, 37209147800, 147012850512, 577741491404, 2284848892872, 8993216244896, 35595538140656, 140288753584200, 555662416386840

Offset

0,2

Comments

Is there a formula analogous to the (conjectured) formula for A060900?

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

M. Bousquet-Mélou, Plane lattice walks avoiding a quadrant, arXiv:1511.02111 [math.CO], 2015.

Mireille Bousquet-Mélou, Square lattice walks avoiding a quadrant, Journal of Combinatorial Theory, Series A, Elsevier, 2016, Special issue for the 50th anniversary of the journal, 144, pp. 37-79. Also <hal-01225710v3>. See App. A.

Kilian Raschel, Amélie Trotignon, On walks avoiding a quadrant, arXiv:1807.08610 [math.CO], 2018.

Crossrefs

Cf. A005566, A001700, A060897, A060899, A060900.

Sequence in context: A192247 A118896 A145211 * A180142 A363545 A302171

Adjacent sequences: A060895 A060896 A060897 * A060899 A060900 A060901

Keyword

nonn,easy,walk

Author

David W. Wilson, May 05 2001

Status

approved