A218633 Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..3 nX3 array

7, 63, 511, 4087, 32689, 261505, 2092027, 16736081, 133887639, 1071093011, 8568679227, 68548914887, 548387167731, 4387064131261, 35096247367295, 280767853492265, 2246125824498091, 17968870569494163, 143749876352266497

Offset

1,1

Comments

Column 3 of A218638

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +7*a(n-4) +7*a(n-5) +3*a(n-6) +21*a(n-7) +6*a(n-8) +6*a(n-9) +6*a(n-10) +6*a(n-11) +3*a(n-12) +9*a(n-13) -9*a(n-14) -9*a(n-15) -9*a(n-16) -9*a(n-17) -9*a(n-18) -9*a(n-19)

Example

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

Crossrefs

Sequence in context: A218191 A218367 A218314 * A218283 A218237 A024088

Adjacent sequences: A218630 A218631 A218632 * A218634 A218635 A218636

Keyword

nonn

Author

R. H. Hardin Nov 03 2012

Status

approved