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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A281401 Number of 2 X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
0, 0, 10, 52, 170, 484, 1296, 3308, 8222, 19996, 47894, 113320, 265560, 617472, 1426498, 3277796, 7497418, 17082444, 38791072, 87831508, 198365446, 447006060, 1005324158, 2257048752, 5059420328, 11325490728, 25320461706, 56545544372 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) + a(n-2) - 16*a(n-3) - a(n-4) + 30*a(n-5) + 4*a(n-6) - 24*a(n-7) - 4*a(n-8) + 8*a(n-9) for n>10.
Empirical g.f.: 2*x^3*(1 + 2*x - 2*x^3)*(5 - 4*x - 16*x^2 - 2*x^3 + 12*x^4) / ((1 - 2*x)*(1 - x - 3*x^2 + 2*x^4)^2). - Colin Barker, Feb 18 2019
EXAMPLE
Some solutions for n=4:
..0..1..0..1. .0..1..1..1. .0..0..0..0. .0..0..0..1. .0..0..1..1
..0..0..0..0. .0..1..0..0. .1..0..1..0. .1..0..1..0. .1..1..0..1
CROSSREFS
Row 2 of A281400.
Sequence in context: A028994 A257042 A092966 * A050494 A367460 A200035
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 21 2017
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 06:44 EDT 2024. Contains 371265 sequences. (Running on oeis4.)