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A060898 Number of walks of length n on square lattice, starting at origin, staying in first, second and third quadrants. 5
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 (list; graph; refs; listen; history; text; internal format)
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 A302171 A045501

Adjacent sequences:  A060895 A060896 A060897 * A060899 A060900 A060901

KEYWORD

nonn,easy,walk

AUTHOR

David W. Wilson, May 05 2001

STATUS

approved

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Last modified December 8 01:42 EST 2019. Contains 329850 sequences. (Running on oeis4.)