A280553 Number of n X 7 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

13, 400, 1316, 3182, 6386, 11697, 20334, 34360, 57389, 95548, 159360, 266756, 448302, 755986, 1278112, 2164458, 3668734, 6220179, 10544150, 17865068, 30247639, 51170104, 86486508, 146040766, 246372038, 415246118, 699240242

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 12*a(n-4) - 12*a(n-5) - 3*a(n-6) + 6*a(n-7) - a(n-9) for n>12.

Empirical g.f.: x*(13 + 322*x - 928*x^2 + 21*x^3 + 930*x^4 + 341*x^5 - 79*x^6 - 480*x^7 - 148*x^8 - 205*x^9 - 238*x^10 + 6*x^11) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

Example

Some solutions for n=4:
..0..1..1..1..0..1..0. .0..1..0..1..0..1..0. .0..0..1..0..1..1..0
..0..0..1..0..1..0..1. .0..1..0..1..0..1..1. .1..1..0..1..0..0..1
..0..1..0..1..0..1..0. .1..0..1..0..1..0..0. .0..0..1..0..1..1..1
..1..0..1..0..1..0..1. .0..0..0..1..0..1..1. .1..1..0..1..0..0..1

Crossrefs

Column 7 of A280554.

Sequence in context: A009010 A171196 A286189 * A162446 A284824 A075672

Adjacent sequences: A280550 A280551 A280552 * A280554 A280555 A280556

Keyword

nonn

Author

R. H. Hardin, Jan 05 2017

Status

approved