A221458 Number of 0..7 arrays of length n with each element unequal to at least one neighbor, with new values introduced in 0..7 order.

0, 1, 2, 7, 25, 102, 456, 2219, 11639, 65320, 389533, 2451393, 16164044, 110866328, 785411383, 5709898562, 42358751505, 319155928942, 2433165471304, 18714220718157, 144885627697659, 1127182676182780, 8800901309557829

Offset: 1

Author

R. H. Hardin Jan 17 2013

Keywords

• nonn

Comments

Column 7 of A221459

Examples

			Some solutions for n=6
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..2....1....1....2....0....2....0....0....2....1....1....0....2....2....0....2
..3....2....0....3....1....2....1....2....0....2....2....0....0....2....0....1
..0....1....0....3....2....1....2....2....3....0....2....2....1....3....2....1
..2....0....2....2....1....0....3....1....4....3....0....0....0....1....1....0
		

Links

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

Formula

Empirical: a(n) = 22*a(n-1) -168*a(n-2) +440*a(n-3) +421*a(n-4) -2898*a(n-5) -924*a(n-6) +7944*a(n-7) +5931*a(n-8) -6610*a(n-9) -10562*a(n-10) -5040*a(n-11) -840*a(n-12)