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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
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
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 02 2020
STATUS
approved

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Last modified June 12 16:34 EDT 2024. Contains 373334 sequences. (Running on oeis4.)