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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A228755 Number of 3 X n binary arrays with top left element equal to 1 and no two ones adjacent horizontally or antidiagonally. 1
 4, 8, 39, 126, 482, 1712, 6277, 22700, 82580, 299648, 1088499, 3952186, 14352786, 52119040, 189266297, 687294648, 2495834292, 9063317432, 32912374319, 119517358582, 434013128786, 1576067091632, 5723300581661, 20783486354532 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - a(n-4). Empirical g.f.: x*(2 - x)*(2 + x) / (1 - 2*x - 6*x^2 + x^4). - Colin Barker, Sep 12 2018 EXAMPLE Some solutions for n=4: ..1..0..0..0....1..0..1..0....1..0..0..1....1..0..0..0....1..0..1..0 ..1..0..1..0....0..0..0..0....0..0..0..0....0..0..0..1....0..0..0..1 ..0..0..0..0....0..1..0..1....0..1..0..1....0..1..0..0....1..0..0..1 CROSSREFS Row 3 of A228754. Sequence in context: A032056 A214535 A321717 * A007215 A195677 A062753 Adjacent sequences: A228752 A228753 A228754 * A228756 A228757 A228758 KEYWORD nonn AUTHOR R. H. Hardin, Sep 02 2013 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.

Last modified May 29 20:53 EDT 2023. Contains 363042 sequences. (Running on oeis4.)