A281691 Number of nX4 0..2 arrays with no element equal to more than one of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

1, 272, 14575, 402470, 8944910, 173467508, 3105145787, 52667675560, 858903297578, 13596253940088, 210237550445094, 3189789818725966, 47643526224223527, 702294154680069306, 10236443706663641968

Offset

1,2

Comments

Column 4 of A281693.

Links

R. H. Hardin, Table of n, a(n) for n = 1..108

Formula

Empirical: a(n) = 39*a(n-1) -498*a(n-2) +1702*a(n-3) +7905*a(n-4) -32790*a(n-5) -94908*a(n-6) +137802*a(n-7) +771006*a(n-8) +1162035*a(n-9) -1500231*a(n-10) -10059165*a(n-11) -13088030*a(n-12) +4591782*a(n-13) +33514611*a(n-14) +51716089*a(n-15) +5010831*a(n-16) -69050808*a(n-17) +1484562*a(n-18) +31250520*a(n-19) -93365307*a(n-20) -104215626*a(n-21) -191236245*a(n-22) +203634639*a(n-23) +629834759*a(n-24) -508901055*a(n-25) -305399139*a(n-26) +1051517480*a(n-27) -255839424*a(n-28) -796011660*a(n-29) +256165674*a(n-30) +72219099*a(n-31) -168291057*a(n-32) -50445873*a(n-33) +81805794*a(n-34) +128612556*a(n-35) +64894427*a(n-36) +18006399*a(n-37) -10587519*a(n-38) -21190079*a(n-39) -17373687*a(n-40) -10932123*a(n-41) -5321814*a(n-42) -2277054*a(n-43) -820917*a(n-44) -241448*a(n-45) -63219*a(n-46) -11661*a(n-47) -2197*a(n-48) for n>56

Example

Some solutions for n=3
..0..1..2..2. .0..1..0..1. .0..1..0..2. .0..1..0..2. .0..0..1..0
..2..0..0..1. .0..2..2..2. .0..2..0..1. .0..2..2..0. .0..1..0..2
..0..1..1..1. .2..0..1..1. .2..0..1..0. .2..1..2..0. .0..2..0..1

Crossrefs

Cf. A281693.

Sequence in context: A250341 A168372 A023907 * A035842 A000518 A230531

Adjacent sequences: A281688 A281689 A281690 * A281692 A281693 A281694

Keyword

nonn

Author

R. H. Hardin, Jan 27 2017

Status

approved