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A333246 Number of self-avoiding closed paths on an n X n grid which pass through NW corner. 6
1, 7, 97, 4111, 532269, 212372937, 263708907211, 1013068026356375 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

From Seiichi Manyama, Apr 07 2020: (Start)

a(11) = 432101605951906251627393.

a(13) = 16149888968763663448192636077980753. (End)

LINKS

Table of n, a(n) for n=2..9.

FORMULA

a(n) = A333439(n) - 1 for n > 1.

EXAMPLE

a(2) = 1;

   +--*

   |  |

   *--*

a(3) = 7;

   +--*      +--*--*   +--*--*   +--*

   |  |      |     |   |     |   |  |

   *--*      *--*--*   *     *   *  *

                       |     |   |  |

                       *--*--*   *--*

   +--*--*   +--*--*   +--*

   |     |   |     |   |  |

   *  *--*   *--*  *   *  *--*

   |  |         |  |   |     |

   *--*         *--*   *--*--*

PROG

(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)])

CROSSREFS

Cf. A140517, A333247, A333323, A333438, A333439, A333466.

Sequence in context: A046908 A005014 A201063 * A335922 A157035 A022008

Adjacent sequences:  A333243 A333244 A333245 * A333247 A333248 A333249

KEYWORD

nonn,more

AUTHOR

Seiichi Manyama, Mar 23 2020

STATUS

approved

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Last modified April 22 22:19 EDT 2021. Contains 343197 sequences. (Running on oeis4.)