A280280 Number of n X 3 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

1, 46, 996, 16860, 259040, 3753846, 52433492, 713549156, 9525564453, 125290653912, 1628677694816, 20969760499276, 267857168480060, 3398651430782436, 42877264217760487, 538272025956290688

Offset

1,2

Comments

Column 3 of A280284.

Links

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

Formula

Empirical: a(n) = 20*a(n-1) -48*a(n-2) -636*a(n-3) +286*a(n-4) +4870*a(n-5) +2994*a(n-6) -7250*a(n-7) -20395*a(n-8) -27254*a(n-9) +18145*a(n-10) +42436*a(n-11) +25187*a(n-12) +8976*a(n-13) -53063*a(n-14) +3942*a(n-15) +11087*a(n-16) -3576*a(n-17) +616*a(n-18) -6944*a(n-19) -48*a(n-20) +512*a(n-21) -384*a(n-22) -256*a(n-24) for n>25.

Example

Some solutions for n=4
..0..1..2. .0..1..1. .0..0..1. .0..1..2. .0..1..2. .0..1..1. .0..1..0
..2..2..0. .1..2..0. .1..1..0. .1..0..1. .0..1..0. .1..2..0. .1..2..0
..0..0..1. .0..1..0. .1..0..2. .0..0..2. .1..2..2. .2..2..2. .0..1..0
..1..0..2. .0..0..1. .2..1..2. .2..1..1. .1..1..0. .1..1..0. .1..0..1

Crossrefs

Cf. A280284.

Sequence in context: A002138 A205495 A281655 * A010962 A057465 A035718

Adjacent sequences: A280277 A280278 A280279 * A280281 A280282 A280283

Keyword

nonn

Author

R. H. Hardin, Dec 30 2016

Status

approved