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

Author

David W. Wilson, May 05 2001

Keywords

• nonn
• easy
• walk

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 . 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.