A333605 Number of directed Hamiltonian walks from NW to SW corners of a 9 X (2*n+1) grid.

1, 128, 28002, 7503654, 2087813834, 585874869236, 164719994049404, 46331085939142414, 13032851914297031372, 3666193548666012258524, 1031319586988812684556890, 290115923359022569718438776, 81611236566429170178900484740, 22957699681804739055041075650848

Offset: 0

Author

Seiichi Manyama, Mar 28 2020

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..200

Crossrefs

Row n=9 of A271592 (with 0 omitted).

Cf. A333584.

Programs

Python

# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A271592(n, k):
    if k == 1: return 1
    universe = tl.grid(k - 1, n - 1)
    GraphSet.set_universe(universe)
    start, goal = 1, n
    paths = GraphSet.paths(start, goal, is_hamilton=True)
    return paths.len()
def A333605(n):
    return A271592(9, 2 * n + 1)
print([A333605(n) for n in range(15)])