A280551 Number of n X 5 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.

2, 87, 325, 832, 1764, 3438, 6386, 11506, 20389, 35757, 62317, 108150, 187115, 322925, 556071, 955574, 1638882, 2805542, 4794088, 8178068, 13927945, 23683803, 40214243, 68187902, 115469449, 195294823, 329919371, 556731676, 938492304

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*(2 + 75*x - 173*x^2 - 84*x^3 + 213*x^4 + 193*x^5 - 84*x^6 - 209*x^7 + 64*x^8 + 25*x^9 - 76*x^10 + 2*x^11) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

Example

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

Crossrefs

Column 5 of A280554.

Sequence in context: A317372 A358807 A177318 * A283945 A172736 A244386

Adjacent sequences: A280548 A280549 A280550 * A280552 A280553 A280554

Keyword

nonn

Author

R. H. Hardin, Jan 05 2017

Status

approved