A252855 - OEIS

A252855

Number of (n+2) X (2+2) 0..2 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.

279, 432, 738, 1296, 2502, 4986, 9936, 20052, 40770, 82872, 168516, 343062, 698688, 1422756, 2897190, 5900472, 12017268, 24474006, 49843512, 101512980, 206743590, 421055928, 857529828, 1746463734, 3556879416, 7244001396, 14753268774

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OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: 9*x*(31 + 17*x + 3*x^2 - 79*x^3 - 123*x^4 - 69*x^5 + 26*x^6 + 92*x^7 + 52*x^8) / ((1 - x)*(1 + x + x^2)*(1 - x - x^2 - 2*x^3 - 2*x^4 + 2*x^5 + 2*x^6)). - Colin Barker, Dec 07 2018

EXAMPLE

Some solutions for n=4:

..0..1..0..0....0..1..0..1....0..1..0..0....0..1..1..2....0..1..0..1

..2..0..0..1....1..1..0..0....2..2..0..0....2..2..1..1....0..1..1..2

..2..1..1..0....0..0..1..0....2..1..2..1....2..2..0..2....1..2..1..2

..0..0..1..1....1..0..0..2....1..2..2..1....1..0..0..2....1..1..0..0

..0..0..2..0....0..1..1..2....1..2..1..2....1..2..2..0....2..2..0..0

..1..2..2..0....1..1..0..0....0..0..2..2....2..0..2..2....2..2..1..1

CROSSREFS

Column 2 of A252861.

Sequence in context: A062384 A053345 A032505 * A331265 A038656 A160116

Adjacent sequences: A252852 A252853 A252854 * A252856 A252857 A252858

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 23 2014

STATUS

approved