login
A256813
Number of length n+5 0..1 arrays with at most two downsteps in every 5 consecutive neighbor pairs.
1
63, 124, 245, 484, 956, 1888, 3728, 7362, 14539, 28712, 56701, 111974, 221128, 436688, 862380, 1703044, 3363203, 6641716, 13116185, 25902088, 51151928, 101015784, 199487860, 393952358, 777984487, 1536378320, 3034068649
OFFSET
1,1
COMMENTS
Column 5 of A256816.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) -a(n-2) +2*a(n-3) -a(n-4) +2*a(n-5) -a(n-6).
Empirical g.f.: x*(63 - 2*x + 60*x^2 - 8*x^3 + 48*x^4 - 32*x^5) / (1 - 2*x + x^2 - 2*x^3 + x^4 - 2*x^5 + x^6). - Colin Barker, Jan 24 2018
EXAMPLE
Some solutions for n=4:
..1....1....0....0....0....1....0....1....1....1....0....1....0....1....0....1
..1....0....1....1....1....0....1....1....0....0....0....0....0....1....0....0
..0....0....1....1....1....0....0....0....0....1....0....0....1....1....1....0
..0....0....0....1....0....0....1....0....0....1....0....1....0....1....0....0
..0....0....0....0....0....0....1....0....1....1....1....1....0....1....1....0
..1....1....1....0....1....0....0....0....0....0....1....0....1....1....1....1
..1....0....1....0....0....1....1....0....1....0....1....0....1....0....1....0
..0....1....1....1....1....0....0....1....1....0....0....0....0....0....1....0
..1....1....0....0....1....0....0....0....1....0....0....0....1....1....1....0
CROSSREFS
Cf. A256816.
Sequence in context: A274460 A181556 A096023 * A324488 A080947 A023720
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2015
STATUS
approved