A218199 Hilltop maps: number of n X 1 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..2 n X 1 array.

1, 3, 7, 13, 25, 49, 97, 191, 375, 737, 1449, 2849, 5601, 11011, 21647, 42557, 83665, 164481, 323361, 635711, 1249775, 2456993, 4830321, 9496161, 18668961, 36702211, 72154647, 141852301, 278874281, 548252401, 1077835841, 2118969471, 4165784295, 8189716289, 16100558297

Offset

1,2

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5).

Empirical g.f.: x*(1 + x + x^2)^2 / (1 - x - x^2 - x^3 - x^4 - x^5). - Colin Barker, Feb 18 2018

Example

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

Crossrefs

Column 1 of A218206.

Sequence in context: A336726 A201081 A017994 * A275788 A169914 A078000

Adjacent sequences: A218196 A218197 A218198 * A218200 A218201 A218202

Keyword

nonn

Author

R. H. Hardin, Oct 23 2012

Status

approved