login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A067964 Number of binary arrangements without adjacent 1's on n X n array connected n-s nw-se. 11
2, 8, 90, 1876, 103484, 11462588, 3118943536, 1808994829500, 2465526600093372, 7394315828592829424, 50975951518289853305508, 784977037926751747674903856, 27509351187362150581313065415008 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 1..18

V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 69-71.

FORMULA

Limit n->infinity (a(n))^(1/n^2) = 1.503048082... (see A085850)

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, 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, ne-sw n-s nw-se A067959, 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: A131349 A319124 A294194 * A102895 A297451 A295773

Adjacent sequences:  A067961 A067962 A067963 * A067965 A067966 A067967

KEYWORD

nonn,nice,hard

AUTHOR

R. H. Hardin, Feb 02 2002

EXTENSIONS

Terms a(14)-a(18) from Vaclav Kotesovec, May 01 2012

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 27 15:59 EST 2020. Contains 332307 sequences. (Running on oeis4.)