A231998 - OEIS

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.

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

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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) + 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