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A231998 Number of (1+1) X (n+1) 0..1 arrays with no element having a strict majority of its horizontal and antidiagonal neighbors equal to one. 1
4, 6, 16, 39, 81, 168, 361, 780, 1681, 3612, 7744, 16620, 35721, 76755, 164836, 354006, 760384, 1633275, 3508129, 7535088, 16184529, 34762680, 74666881, 160377096, 344473600, 739894200, 1589218225, 3413480691, 7331811876, 15747991350 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(4 + 2*x + 10*x^2 + 11*x^3 + 12*x^4 + 9*x^5 - 2*x^6 - 7*x^7 - 3*x^8) / ((1 + x^2 - x^3)*(1 + x^2 + x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Oct 01 2018

EXAMPLE

Some solutions for n=7:

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

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

CROSSREFS

Row 1 of A231997.

Sequence in context: A076066 A227178 A165799 * A056421 A032295 A072279

Adjacent sequences:  A231995 A231996 A231997 * A231999 A232000 A232001

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 16 2013

STATUS

approved

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Last modified November 27 02:30 EST 2020. Contains 338677 sequences. (Running on oeis4.)