A333604 - OEIS

%I #20 Jun 25 2023 21:08:55

%S 1,1,64,264,6820,52387,909009,8934966,130373192,1440623260,

%T 19338414411,226336038320,2916455246831,35119270968805,

%U 443497762883269,5416278334971240,67721300861621626,832844111255909543,10362230473284966919

%N Number of directed Hamiltonian walks from NW to SW corners of an 8 X n grid.

%H Ed Wynn, <a href="/A333604/b333604.txt">Table of n, a(n) for n = 1..89</a>

%o (Python)

%o # Using graphillion

%o from graphillion import GraphSet

%o import graphillion.tutorial as tl

%o def A271592(n, k):

%o     if k == 1: return 1

%o     universe = tl.grid(k - 1, n - 1)

%o     GraphSet.set_universe(universe)

%o     start, goal = 1, n

%o     paths = GraphSet.paths(start, goal, is_hamilton=True)

%o     return paths.len()

%o def A333604(n):

%o     return A271592(8, n)

%o print([A333604(n) for n in range(1, 9)])

%Y Row n=8 of A271592.

%Y Cf. A333583.

%K nonn

%O 1,3

%A _Seiichi Manyama_, Mar 28 2020

%E More terms from _Ed Wynn_, Jun 25 2023