A067959 Number of binary arrangements without adjacent 1's on n X n torus connected ne-sw n-s nw-se.

1, 7, 22, 547, 9021, 812830, 70046159, 24082448515, 10363980496342, 14228018243052057, 29400555005986658803, 166705587265151114516638, 1606507128309318588452521527, 38505096862341023166325442747581, 1696028983502674228038462924646464012

Offset

1,2

Links

Sean A. Irvine, Table of n, a(n) for n = 1..17

V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 73.

Example

Neighbors for n=4 (dots represent spaces):
.\|/\|/\|/\|/
. o..o..o..o
./|\/|\/|\/|\
.\|/\|/\|/\|/
. o..o..o..o
./|\/|\/|\/|\
.\|/\|/\|/\|/
. o..o..o..o
./|\/|\/|\/|\
.\|/\|/\|/\|/
. o..o..o..o
./|\/|\/|\/|\

Crossrefs

Cf. circle A000204, line A000045, arrays: ne-sw nw-se A067965, e-w ne-sw nw-se A067963, n-s nw-se A067964, e-w n-s nw-se A066864, e-w ne-sw n-s nw-se A063443, n-s A067966, e-w n-s A006506, nw-se A067962, toruses: bare A002416, ne-sw nw-se A067960, e-w ne-sw n-s nw-se A067958, n-s A067961, e-w n-s A027683, e-w ne-sw n-s A066866.

Sequence in context: A197991 A197853 A087184 * A273216 A367002 A070411

Adjacent sequences: A067956 A067957 A067958 * A067960 A067961 A067962

Keyword

nonn,hard

Author

R. H. Hardin, Feb 02 2002

Extensions

a(13) from Vaclav Kotesovec, Aug 22 2016

a(14) from Vaclav Kotesovec, May 24 2021

a(15) from Sean A. Irvine, Jan 14 2024

Status

approved