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A333247
Number of self-avoiding closed paths on an n X n grid which pass through NW and SW corners.
5
1, 4, 47, 1843, 232905, 92729439, 115234959344, 442748883422394
OFFSET
2,2
COMMENTS
a(11) = 188829168009674568016545. - Seiichi Manyama, Apr 07 2020
EXAMPLE
a(2) = 1;
+--*
| |
+--*
a(3) = 4;
+--*--* +--*--* +--* +--*
| | | | | | | |
* * * *--* * *--* * *
| | | | | | | |
+--*--* +--* +--*--* +--*
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A333247(n):
universe = tl.grid(n - 1, n - 1)
GraphSet.set_universe(universe)
cycles = GraphSet.cycles().including(1).including(n)
return cycles.len()
print([A333247(n) for n in range(2, 10)])
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Mar 23 2020
STATUS
approved