A243640 Number of length n+2 0..9 arrays with no three unequal elements in a row and new values 0..9 introduced in 0..9 order.

4, 9, 21, 51, 127, 324, 844, 2243, 6073, 16737, 46905, 133556, 386062, 1132107, 3365627, 10137559, 30920943, 95457177, 298128257, 941574130, 3006037464, 9697650031, 31602766791, 104000078093, 345512414521, 1158493006765

Offset: 1

Author

R. H. Hardin, Jun 08 2014

Keywords

• nonn

Comments

Column 9 of A243641

Examples

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

Links

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

Formula

Empirical: a(n) = 17*a(n-1) -99*a(n-2) +125*a(n-3) +931*a(n-4) -3185*a(n-5) -1785*a(n-6) +19063*a(n-7) -6754*a(n-8) -56936*a(n-9) +32132*a(n-10) +99764*a(n-11) -41096*a(n-12) -100896*a(n-13) +5152*a(n-14) +42048*a(n-15) +11520*a(n-16)