A219423 Unchanging value maps: number of 3 X n binary arrays indicating the locations of corresponding elements unequal to no horizontal or antidiagonal neighbor in a random 0..2 3 X n array.

1, 21, 93, 453, 2121, 9926, 46776, 220655, 1041073, 4909754, 23155430, 109215035, 515130861, 2429644852, 11459531527, 54049709552, 254929619681, 1202393496717, 5671171946685, 26748483522662, 126161124832462, 595047865009759

Offset

1,2

Comments

Row 3 of A219421.

Links

R. H. Hardin, Table of n, a(n) for n = 1..94

Formula

Empirical: a(n) = 4*a(n-1) +a(n-2) +7*a(n-3) +36*a(n-4) -62*a(n-5) -78*a(n-6) +88*a(n-7) -121*a(n-8) -110*a(n-9) +325*a(n-10) -31*a(n-11) -175*a(n-12) +320*a(n-13) -17*a(n-14) -193*a(n-15) +107*a(n-16) -108*a(n-17) +7*a(n-18) +a(n-19) -46*a(n-20) +22*a(n-21) +10*a(n-22) +6*a(n-23) +8*a(n-24) for n>26.

Example

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

Crossrefs

Cf. A219421.

Sequence in context: A144856 A065522 A218844 * A123213 A296822 A174084

Adjacent sequences: A219420 A219421 A219422 * A219424 A219425 A219426

Keyword

nonn

Author

R. H. Hardin, Nov 19 2012

Status

approved