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

1,1

Comments

Column 9 of A243641

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)

Example

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

Crossrefs

Sequence in context: A243637 A243638 A243639 * A243634 A076861 A048391

Adjacent sequences: A243637 A243638 A243639 * A243641 A243642 A243643

Keyword

nonn

Author

R. H. Hardin, Jun 08 2014

Status

approved