A268321 Number of length-(n+1) 0..2 arrays with new values introduced in sequential order, and with new repeated values introduced in sequential order, both starting with zero.

2, 4, 10, 25, 66, 177, 485, 1348, 3797, 10812, 31076, 90015, 262432, 769199, 2264475, 6690450, 19825011, 58884842, 175238730, 522316253, 1558776782, 4656673837, 13922711281, 41654206400, 124688153137, 373402997944, 1118614401040

Offset: 1

Author

R. H. Hardin, Feb 01 2016

Keywords

• nonn

Examples

			Some solutions for n=10:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..0....0....1....0....0....1....0....1....0....0....0....0....0....1....1....1
..1....0....0....1....0....0....1....2....1....1....1....1....1....0....0....2
..2....0....2....1....1....2....1....0....2....1....1....0....2....2....1....1
..1....0....0....2....1....0....1....0....1....0....0....1....0....0....2....0
..2....1....0....1....1....1....1....0....1....2....1....1....2....0....0....1
..1....1....2....1....1....2....1....1....2....2....0....1....1....2....1....0
..1....0....0....0....1....0....0....2....0....0....0....2....2....1....2....0
..2....1....0....2....2....2....0....0....0....2....1....2....0....1....1....0
..1....2....2....1....0....0....2....1....1....0....2....1....0....2....2....2
..1....1....1....1....0....2....2....0....1....1....0....2....1....0....1....0
		

Links

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

Crossrefs

Column 2 of A268327.

Formula

Empirical: a(n) = 7*a(n-1) - 14*a(n-2) + 21*a(n-4) - 7*a(n-5) - 6*a(n-6).

Empirical g.f.: x*(2 - 10*x + 10*x^2 + 11*x^3 - 11*x^4 - 5*x^5) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - 3*x)*(1 - 2*x - x^2)). - Colin Barker, Jan 13 2019