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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A196630 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 1,3,2,0,4 for x=0,1,2,3,4. 3
 1, 2, 5, 10, 26, 65, 161, 403, 1006, 2511, 6270, 15654, 39083, 97579, 243625, 608258, 1518637, 3791578, 9466426, 23634809, 59008985, 147327627, 367832622, 918367047, 2292885358, 5724642758, 14292705299, 35684571667, 89093606033, 222439846274 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Every 0 is next to 0 1's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 0's, every 4 is next to 4 4's. Column 2 of A196636. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 2*a(n-1) + a(n-2) + a(n-3) - a(n-4). Empirical g.f.: x*(1 - 3*x^3) / (1 - 2*x - x^2 - x^3 + x^4). - Colin Barker, Feb 22 2018 EXAMPLE All solutions for n=4: ..0..0....0..0....0..0....0..0....0..0....0..0....2..2....0..0....0..0....0..0 ..3..0....0..3....3..0....0..0....0..0....0..0....2..2....0..3....0..0....2..2 ..0..0....0..0....0..3....3..0....2..2....0..3....0..0....3..0....0..0....2..2 ..0..0....0..0....0..0....0..0....2..2....0..0....0..0....0..0....0..0....0..0 CROSSREFS Cf. A196636. Sequence in context: A354832 A115725 A305577 * A079572 A053391 A183956 Adjacent sequences: A196627 A196628 A196629 * A196631 A196632 A196633 KEYWORD nonn AUTHOR R. H. Hardin, Oct 04 2011 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 April 19 08:39 EDT 2024. Contains 371782 sequences. (Running on oeis4.)