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!)
 A275260 Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,1) or (-1,-1) and new values introduced in order 0..2. 1
 2, 9, 24, 64, 172, 476, 1320, 3672, 10220, 28472, 79376, 221320, 617160, 1720976, 4799104, 13382832, 37319536, 104069760, 290210016, 809282592, 2256773088, 6293258240, 17549436800, 48938515904, 136470379968, 380562509568 (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) = 4*a(n-1) - 2*a(n-2) - 6*a(n-3) + 6*a(n-4) + 4*a(n-5) - 16*a(n-6) + 12*a(n-7) + 8*a(n-8) - 8*a(n-9) for n>10. Empirical g.f.: x*(2 + x - 8*x^2 - 2*x^3 + 6*x^4 - 2*x^5 - 4*x^6 + 16*x^7 - 8*x^9) / (1 - 4*x + 2*x^2 + 6*x^3 - 6*x^4 - 4*x^5 + 16*x^6 - 12*x^7 - 8*x^8 + 8*x^9). - Colin Barker, Feb 02 2019 EXAMPLE Some solutions for n=4: ..0..0. .0..0. .0..0. .0..0. .0..1. .0..0. .0..1. .0..1. .0..1. .0..1 ..1..1. .1..2. .0..1. .1..1. .0..2. .1..1. .0..1. .1..1. .2..1. .0..2 ..1..2. .1..2. .1..2. .1..2. .0..1. .2..2. .0..1. .0..2. .0..1. .0..2 ..2..2. .1..2. .0..2. .0..0. .0..1. .2..0. .0..2. .2..2. .0..1. .1..2 CROSSREFS Column 2 of A275266. Sequence in context: A131357 A274543 A079997 * A248436 A222667 A122006 Adjacent sequences:  A275257 A275258 A275259 * A275261 A275262 A275263 KEYWORD nonn AUTHOR R. H. Hardin, Jul 21 2016 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 April 13 01:36 EDT 2021. Contains 342934 sequences. (Running on oeis4.)