

A333247


Number of selfavoiding closed paths on an n X n grid which pass through NW and SW corners.


5




OFFSET

2,2


COMMENTS



LINKS



EXAMPLE

a(2) = 1;
+*
 
+*
a(3) = 4;
+** +** +* +*
       
* * * ** * ** * *
       
+** +* +** +*


PROG

(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
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



STATUS

approved



