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A333581
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Number of Hamiltonian paths in a 6 X (2n+1) grid starting at the lower left corner and finishing in the upper right corner.
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3
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1, 16, 378, 10204, 286395, 8142184, 232408228, 6641558434, 189856823709, 5427696641303, 155171211771501, 4436158800822989, 126824318787312712, 3625748174071085779, 103655548766966797516, 2963380335725281547187, 84719269552230266413889, 2422015949371169505273833
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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PROG
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(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
if n == 1 or k == 1: return 1
universe = tl.grid(n - 1, k - 1)
GraphSet.set_universe(universe)
start, goal = 1, k * n
paths = GraphSet.paths(start, goal, is_hamilton=True)
return paths.len()
print([A333581(n) for n in range(10)])
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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