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A333689 Number of self-avoiding paths in (2*n+1) X 5 grid starting the upper left corner, passing through the center of grid and finishing the lower right corner. 2
1, 101, 7056, 610765, 53968755, 4775133828, 422813081886, 37441305792927, 3315577406171322, 293609559097456363, 26000534802119070508, 2302473191851860468948, 203895143590466986654399, 18055900558029962460378646, 1598937211532791928425001493, 141593611215040047912334138664 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..500

PROG

(Python)

# Using graphillion

from graphillion import GraphSet

import graphillion.tutorial as tl

def A333685(n, k):

    if n == 0 or k == 0: return 1

    universe = tl.grid(2 * n, 2 * k)

    GraphSet.set_universe(universe)

    start, goal = 1, (2 * n + 1) * (2 * k + 1)

    paths = GraphSet.paths(start, goal).including((start + goal) // 2)

    return paths.len()

def A333689(n):

    return A333685(n, 2)

print([A333689(n) for n in range(15)])

CROSSREFS

Column 2 of A333685.

Sequence in context: A167626 A017764 A217677 * A291990 A303572 A152756

Adjacent sequences:  A333686 A333687 A333688 * A333690 A333691 A333692

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Apr 02 2020

STATUS

approved

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Last modified September 28 04:28 EDT 2022. Contains 357063 sequences. (Running on oeis4.)