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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.
1
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
1,1
LINKS
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
EXAMPLE
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
CROSSREFS
Column 2 of A268327.
Sequence in context: A230552 A230555 A189912 * A195981 A124500 A220872
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 01 2016
STATUS
approved