A228734 Number of arrays of the median of three adjacent elements of some length n+2 0..2 array.

3, 9, 27, 77, 185, 447, 1071, 2593, 6333, 15513, 38039, 93213, 228279, 558849, 1367945, 3348489, 8196847, 20065943, 49122291, 120253773, 294386457, 720668887, 1764221329, 4318870217, 10572732933, 25882394413, 63360952825, 155109705901

Offset

1,1

Links

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

Formula

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

Example

Some solutions for n=4
..1..1..2..0..1..2..1..0..2..1..0..2..0..0..0..1
..2..2..1..2..2..1..0..2..2..2..0..1..2..2..1..0
..1..0..2..0..1..2..0..1..1..1..0..0..2..1..0..1
..1..0..0..0..2..2..0..1..1..0..2..1..1..2..0..2

Crossrefs

Column 2 of A228740.

Sequence in context: A361423 A135415 A182897 * A048481 A269488 A027027

Adjacent sequences: A228731 A228732 A228733 * A228735 A228736 A228737

Keyword

nonn

Author

R. H. Hardin Sep 01 2013

Status

approved