A212226 Number of 0..2 arrays of length n+3 with sum no more than 4 in any length 4 subsequence (=50% duty cycle).

50, 124, 311, 775, 1895, 4663, 11518, 28446, 70145, 172951, 426630, 1052487, 2596184, 6403675, 15795627, 38963018, 96109484, 237070048, 584773118, 1442444418, 3558040343, 8776520278, 21648797430, 53400493513, 131721540000

Offset

1,1

Comments

Column 2 of A212232.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +a(n-3) +6*a(n-4) -3*a(n-5) -a(n-6) +a(n-7) -7*a(n-8) +4*a(n-9) -a(n-10) +3*a(n-12) -4*a(n-13) -a(n-16) +a(n-17).

Example

Some solutions for n=3
..0....0....2....1....0....1....1....1....0....1....1....0....1....1....1....1
..0....1....1....2....1....2....1....1....1....0....1....2....2....1....0....0
..1....0....1....1....0....0....2....0....0....0....0....2....0....1....1....0
..0....0....0....0....0....1....0....1....0....2....2....0....1....1....0....1
..2....0....2....0....2....0....1....0....1....1....1....0....1....0....2....2
..1....0....1....0....0....0....1....1....0....1....0....2....2....1....1....0

Crossrefs

Cf. A212232.

Sequence in context: A044618 A248531 A222822 * A031397 A045181 A093194

Adjacent sequences: A212223 A212224 A212225 * A212227 A212228 A212229

Keyword

nonn

Author

R. H. Hardin, May 06 2012

Status

approved