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A333246
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Number of self-avoiding closed paths on an n X n grid which pass through NW corner.
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6
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OFFSET
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2,2
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COMMENTS
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From Seiichi Manyama, Apr 07 2020: (Start)
a(11) = 432101605951906251627393.
a(13) = 16149888968763663448192636077980753. (End)
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LINKS
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Table of n, a(n) for n=2..9.
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FORMULA
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a(n) = A333439(n) - 1 for n > 1.
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EXAMPLE
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a(2) = 1;
+--*
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*--*
a(3) = 7;
+--* +--*--* +--*--* +--*
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*--* *--*--* * * * *
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*--*--* *--*
+--*--* +--*--* +--*
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* *--* *--* * * *--*
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*--* *--* *--*--*
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PROG
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(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A333246(n):
universe = tl.grid(n - 1, n - 1)
GraphSet.set_universe(universe)
cycles = GraphSet.cycles().including(1)
return cycles.len()
print([A333246(n) for n in range(2, 10)])
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CROSSREFS
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Cf. A140517, A333247, A333323, A333438, A333439, A333466.
Sequence in context: A046908 A005014 A201063 * A335922 A157035 A022008
Adjacent sequences: A333243 A333244 A333245 * A333247 A333248 A333249
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KEYWORD
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nonn,more
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AUTHOR
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Seiichi Manyama, Mar 23 2020
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STATUS
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approved
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