A229398 - OEIS

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

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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