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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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1, 7, 97, 4111, 532269, 212372937, 263708907211, 1013068026356375, 11955420069208095719, 432101605951906251627393, 47778407166747833830058004149, 16149888968763663448192636077980753, 16675786862526496319891707194153887550751, 52568166380872328447478940416604864445574575709
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,2
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LINKS
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FORMULA
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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
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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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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