login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A333515 Number of self-avoiding closed paths on an n X 5 grid which pass through four corners ((0,0), (0,4), (n-1,4), (n-1,0)). 3
1, 7, 49, 373, 3105, 26515, 227441, 1953099, 16782957, 144262743, 1240194297, 10662034451, 91663230249, 788046822891, 6775004473757, 58246174168047, 500755017859261, 4305100014182879, 37011883913816129, 318199242452585915, 2735628331213604009, 23518793814422304163 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

Also number of self-avoiding closed paths on a 5 X n grid which pass through four corners ((0,0), (0,n-1), (4,n-1), (4,0)).

LINKS

Seiichi Manyama, Table of n, a(n) for n = 2..1000

EXAMPLE

a(2) = 1;

+--*--*--*--+

| |

+--*--*--*--+

a(3) = 7;

+--*--*--*--+ +--*--*--*--+ +--*--*--*--+

| | | | | |

* *--* * * *--*--* * * *--* *

| | | | | | | | | | | |

+--*--* *--+ +--* *--+ +--* *--*--+

+--*--*--*--+ +--*--* *--+ +--* *--*--+

| | | | | | | | | |

* * * *--* * * *--* *

| | | | | |

+--*--*--*--+ +--*--*--*--+ +--*--*--*--+

+--* *--+

| | | |

* *--*--* *

| |

+--*--*--*--+

PROG

(Python)

# Using graphillion

from graphillion import GraphSet

import graphillion.tutorial as tl

def A333513(n, k):

universe = tl.grid(n - 1, k - 1)

GraphSet.set_universe(universe)

cycles = GraphSet.cycles()

for i in [1, k, k * (n - 1) + 1, k * n]:

cycles = cycles.including(i)

return cycles.len()

def A333515(n):

return A333513(n, 5)

print([A333515(n) for n in range(2, 25)])

CROSSREFS

Column k=5 of A333513.

Sequence in context: A344270 A144820 A344251 * A324353 A349781 A199554

Adjacent sequences: A333512 A333513 A333514 * A333516 A333517 A333518

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Mar 25 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 3 01:46 EST 2023. Contains 360024 sequences. (Running on oeis4.)