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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A067960 Number of binary arrangements without adjacent 1's on n X n torus connected ne-sw nw-se. 11
 1, 9, 34, 961, 25531, 2722500, 464483559, 224546142769, 215560806324388, 509113406167679889, 2590618817013278596997, 30737628149641669227004804, 809724336154415150287031740151, 48754690373355654118816600200711441 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS If n is odd then A067960(n)=A027683(n-1). a(18) = 2184710661251680812138610069332410066909052859790416601664, (a(17)=?). - Vaclav Kotesovec, Sep 16 2014 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 1..16 V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 440. 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 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. Cf. A212271. Sequence in context: A154393 A119389 A197273 * A119757 A003865 A265377 Adjacent sequences:  A067957 A067958 A067959 * A067961 A067962 A067963 KEYWORD nonn,hard,nice AUTHOR R. H. Hardin, Feb 02 2002 EXTENSIONS Terms a(12)-a(16) from Vaclav Kotesovec, May 18 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.

Last modified February 23 07:11 EST 2020. Contains 332159 sequences. (Running on oeis4.)