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

Author

R. H. Hardin, May 06 2012

Keywords

• nonn

Comments

Column 2 of A212232.

Examples

			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
		

Links

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

Crossrefs

Cf. A212232.

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).