A221571 Number of 0..6 arrays of length n with each element differing from at least one neighbor by something other than 1

0, 37, 197, 1369, 8991, 59705, 395641, 2622817, 17385993, 115249117, 763966685, 5064207645, 33569783613, 222528473325, 1475103973253, 9778217146445, 64818163521317, 429668748357261, 2848202159470085, 18880255015594493

Offset

1,2

Comments

Column 6 of A221573

Links

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

Formula

Empirical: a(n) = 7*a(n-1) -4*a(n-2) +6*a(n-3) +26*a(n-4) +10*a(n-5) +16*a(n-6) +12*a(n-8).

Empirical: -x^2*(37-62*x+138*x^2-26*x^3+100*x^4-36*x^5+48*x^6) / ( -1+7*x-4*x^2+6*x^3+26*x^4+10*x^5+16*x^6+12*x^8 ). - R. J. Mathar, Jun 06 2013

Example

Some solutions for n=6
..4....2....5....0....4....4....2....3....1....3....6....0....5....4....0....2
..6....5....1....2....4....6....5....5....4....1....6....2....0....6....6....2
..2....5....6....5....5....2....2....5....1....0....2....3....0....5....1....5
..4....4....6....2....3....3....5....6....1....0....6....1....6....1....5....1
..6....2....0....5....4....1....1....6....1....0....0....3....4....3....5....4
..6....4....2....5....1....5....6....4....4....4....4....0....2....3....3....2

Crossrefs

Sequence in context: A107196 A140027 A109320 * A053872 A141954 A211734

Adjacent sequences: A221568 A221569 A221570 * A221572 A221573 A221574

Keyword

nonn

Author

R. H. Hardin Jan 20 2013

Status

approved