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A333438
Number of self-avoiding walks of any length from NW corner to its adjacent points on an n X n grid or lattice.
3
4, 16, 196, 8224, 1064540, 424745876, 527417814424, 2026136052712752, 23910840138416191440, 864203211903812503254788, 95556814333495667660116008300, 32299777937527326896385272155961508, 33351573725052992639783414388307775101504, 105136332761744656894957880833209728891149151420
OFFSET
2,1
EXAMPLE
a(2) = 4;
S--E S E
| |
*--*
S S--*
| |
E E--*
a(3) = 16;
S--E S E S E--* S E--*
| | | | | |
*--* *--*--* * *
| |
*--*--*
S E S E--* S E--* S E
| | | | | | | |
* * * *--* *--* * * *--*
| | | | | | | |
*--* *--* *--* *--*--*
S S--* S--* S--*--*
| | | |
E E--* E * E *
| | | |
*--* *--*--*
S--*--* S--*--* S--* S--*--*
| | | |
E--*--* E *--* E *--* E--* *
| | | | | |
*--* *--*--* *--*
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A333438(n):
universe = tl.grid(n - 1, n - 1)
GraphSet.set_universe(universe)
start, goal = 1, 2
paths = GraphSet.paths(start, goal)
return paths.len() * 2
print([A333438(n) for n in range(2, 10)])
CROSSREFS
Sequence in context: A000513 A088027 A271267 * A232840 A113905 A200045
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 21 2020
EXTENSIONS
a(11) and a(13) from Seiichi Manyama
More terms from Ed Wynn, Jun 29 2023
STATUS
approved