A212834 Number of 0..7 arrays of length n+1 with 0 never adjacent to 7.

62, 482, 3746, 29114, 226274, 1758602, 13667858, 106226618, 825593474, 6416514026, 49869159026, 387583197338, 3012297335522, 23411580532682, 181954847741906, 1414153417389434, 10990803008177474, 85420541561578922

Offset: 1

Author

R. H. Hardin, May 28 2012

Keywords

• nonn

Comments

Column 7 of A212835.

Examples

			Some solutions for n=5:
..4....4....2....6....2....4....0....2....4....2....2....0....2....4....2....4
..3....1....2....4....1....0....0....1....6....4....7....5....7....2....5....0
..3....2....0....7....7....2....3....1....0....3....2....6....7....5....2....3
..5....1....1....4....2....6....7....2....3....5....6....1....1....7....1....2
..0....1....6....6....4....4....6....3....2....6....3....5....2....1....4....7
..2....0....2....4....0....3....2....4....2....1....1....3....4....5....5....5
		

Links

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

Crossrefs

Cf. A212835.

Formula

Empirical: a(n) = 7*a(n-1) + 6*a(n-2).

Empirical g.f.: 2*x*(31 + 24*x) / (1 - 7*x - 6*x^2). - Colin Barker, Jul 21 2018