A218593 Hilltop maps: number of 2Xn binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..2 2Xn array

1, 13, 57, 225, 895, 3565, 14189, 56489, 224891, 895325, 3564433, 14190565, 56494859, 224914869, 895421261, 3564812065, 14192074291, 56500867089, 224938787413, 895516488309, 3565191179595, 14193583605661, 56506875907213

Offset

1,2

Comments

Row 2 of A218592

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +3*a(n-2) +3*a(n-3) +a(n-4) +5*a(n-5) +2*a(n-6) +2*a(n-7) +a(n-8) +a(n-9) -a(n-10) -a(n-11) -a(n-12) -a(n-13) for n>14

Example

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

Crossrefs

Sequence in context: A007202 A368813 A222161 * A358303 A212405 A147384

Adjacent sequences: A218590 A218591 A218592 * A218594 A218595 A218596

Keyword

nonn

Author

R. H. Hardin Nov 03 2012

Status

approved