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A333581
Number of Hamiltonian paths in a 6 X (2n+1) grid starting at the lower left corner and finishing in the upper right corner.
3
1, 16, 378, 10204, 286395, 8142184, 232408228, 6641558434, 189856823709, 5427696641303, 155171211771501, 4436158800822989, 126824318787312712, 3625748174071085779, 103655548766966797516, 2963380335725281547187, 84719269552230266413889, 2422015949371169505273833
OFFSET
0,2
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A333580(n, k):
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()
def A333581(n):
return A333580(6, 2 * n + 1)
print([A333581(n) for n in range(10)])
CROSSREFS
Sequence in context: A241106 A027403 A264073 * A201617 A235672 A235729
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 27 2020
EXTENSIONS
Terms a(10) and beyond from Andrew Howroyd, Jan 30 2022
STATUS
approved