A359992 Number of connected spanning subgraphs in the n X n grid graph.

1, 5, 431, 555195, 10286937043, 2692324030864335, 9852929684161379901975, 501079193080617800221189943995, 352690403996687922642590703716802346343, 3426297680513758764075706102615040790667832304415, 458508006189588425325361635000918336126387961057365005349963

Offset

1,2

Comments

For n > 1, a(n) is the number of connected edge covers in the n X n grid graph.

Links

Andrew Howroyd, Table of n, a(n) for n = 1..15

Eric Weisstein's World of Mathematics, Grid Graph

Formula

a(n) = A053765(n) - A359989(n).

Example

The a(2) = 5 connected spanning subgraphs are the following subgraphs and their rotations and reflections.
   o---o   o---o
   |       |   |
   o---o   o---o

Crossrefs

Main diagonal of A359993.

Cf. A007341, A053765, A080691, A286913, A359989.

Sequence in context: A199090 A218393 A038003 * A377724 A054332 A145247

Adjacent sequences: A359989 A359990 A359991 * A359993 A359994 A359995

Keyword

nonn

Author

Andrew Howroyd, Jan 28 2023

Status

approved