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A208704 Number of nX3 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors. 2
4, 28, 196, 1372, 9604, 67228, 470596, 3294172, 23059204, 161414428, 1129900996, 7909306972, 55365148804, 387556041628, 2712892291396, 18990246039772, 132931722278404, 930522055948828, 6513654391641796, 45595580741492572 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A208709.

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1).

Empirical: a(n) = (A198480(n)+1)*2 = (A024075(n)+1)*4. [Martin Ettl, Nov 09 2012; revised Nov 13 2012]

EXAMPLE

Some solutions for n=4

..0..0..0....0..1..1....0..0..1....0..1..1....0..1..1....0..1..1....0..0..1

..1..0..1....1..0..1....0..0..1....0..1..1....1..0..0....1..0..1....0..1..1

..1..0..1....0..1..0....0..0..1....0..1..1....1..1..1....1..1..1....0..0..0

..1..0..1....0..1..0....1..1..1....0..1..1....1..0..1....1..0..1....0..1..0

CROSSREFS

Cf. A270471.

Sequence in context: A155611 A218175 A002903 * A270471 A019482 A198630

Adjacent sequences:  A208701 A208702 A208703 * A208705 A208706 A208707

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 01 2012

STATUS

approved

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Last modified August 13 22:26 EDT 2020. Contains 336464 sequences. (Running on oeis4.)