A229398 Number of n X 4 0..2 arrays with top left element 0, horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and antidiagonal differences never 0.

8, 34, 153, 711, 3357, 15952, 75965, 362012, 1725628, 8226525, 39219624, 186980973, 891444175, 4250029697, 20262368018, 96602551624, 460560895602, 2195763437529, 10468490114235, 49909423013209, 237947448670976, 1134434841904169

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 9*a(n-1) - 28*a(n-2) + 47*a(n-3) - 55*a(n-4) + 47*a(n-5) - 28*a(n-6) + 9*a(n-7) - a(n-8).

Empirical g.f.: x*(1 - x)*(8 - 30*x + 41*x^2 - 49*x^3 + 35*x^4 - 15*x^5 + 2*x^6) / (1 - 9*x + 28*x^2 - 47*x^3 + 55*x^4 - 47*x^5 + 28*x^6 - 9*x^7 + x^8). - Colin Barker, Sep 15 2018

Example

Some solutions for n=4:
..0..2..1..1....0..2..1..0....0..2..1..0....0..2..2..1....0..2..1..1
..0..2..2..1....0..2..2..1....0..2..1..0....0..0..2..2....0..0..2..1
..1..0..2..2....1..0..2..1....0..2..1..1....1..0..0..0....1..1..0..2
..1..1..0..0....1..0..2..1....0..2..2..1....1..1..1..1....2..1..1..0

Crossrefs

Column 4 of A229402.

Sequence in context: A335749 A227330 A252934 * A223015 A222796 A203445

Adjacent sequences: A229395 A229396 A229397 * A229399 A229400 A229401

Keyword

nonn

Author

R. H. Hardin, Sep 22 2013

Status

approved