A256815 Number of length n+7 0..1 arrays with at most two downsteps in every 7 consecutive neighbor pairs.

219, 402, 753, 1424, 2693, 5088, 9613, 18104, 34013, 63928, 120362, 226816, 427341, 804974, 1516179, 2855304, 5376354, 10123582, 19065294, 35907400, 67626166, 127359488, 239852341, 451704432, 850669960, 1602023036, 3017039568

Offset: 1

Author

R. H. Hardin, Apr 10 2015

Keywords

• nonn

Comments

Column 7 of A256816

Examples

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

Links

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

Crossrefs

Cf. A256816

Formula

Empirical: a(n) = 2*a(n-1) -a(n-2) +3*a(n-4) -2*a(n-5) +10*a(n-7) -7*a(n-8) -12*a(n-11) +9*a(n-12) -24*a(n-14) +18*a(n-15)