A219079 Hilltop maps: number of 2Xn binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..1 2Xn array

1, 11, 47, 165, 625, 2435, 9367, 35901, 137865, 529675, 2034399, 7813333, 30009313, 115260115, 442689383, 1700273453, 6530386425, 25081819099, 96333894191, 369997847365, 1421082488529, 5458073486883, 20963291245879, 80515511728413

Offset

1,2

Comments

Row 2 of A219078

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +a(n-2) +7*a(n-3) +6*a(n-4)

Example

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

Crossrefs

Sequence in context: A178572 A036489 A076306 * A059323 A267614 A123984

Adjacent sequences: A219076 A219077 A219078 * A219080 A219081 A219082

Keyword

nonn

Author

R. H. Hardin Nov 11 2012

Status

approved