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

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A280897 Number of n X 3 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1
 0, 10, 646, 22632, 610448, 14262832, 304584096, 6117000704, 117496694272, 2181977379072, 39462274293248, 698659360847872, 12154771113160704, 208386384523096064, 3528538532937736192, 59112926060691652608 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 42*a(n-1) - 564*a(n-2) + 2072*a(n-3) + 4512*a(n-4) + 2688*a(n-5) + 512*a(n-6) for n>8. Empirical g.f.: 2*x^2*(5 + 113*x + 570*x^2 + 1764*x^3 + 2416*x^4 + 1344*x^5 + 256*x^6) / (1 - 14*x - 8*x^2)^3. - Colin Barker, Feb 14 2019 EXAMPLE Some solutions for n=4: ..0..0..0. .0..1..1. .0..1..2. .0..1..0. .0..1..2. .0..0..0. .0..1..2 ..1..0..1. .1..2..0. .2..2..1. .0..1..0. .0..1..2. .1..2..1. .1..1..2 ..2..2..1. .0..0..2. .2..1..1. .2..2..2. .1..1..1. .1..1..2. .0..0..2 ..0..2..0. .0..1..2. .0..0..1. .1..2..0. .0..2..2. .2..0..1. .2..2..0 CROSSREFS Column 3 of A280902. Sequence in context: A209472 A132543 A261328 * A099024 A126680 A249848 Adjacent sequences: A280894 A280895 A280896 * A280898 A280899 A280900 KEYWORD nonn AUTHOR R. H. Hardin, Jan 10 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.

Last modified December 10 19:24 EST 2023. Contains 367717 sequences. (Running on oeis4.)