A243639 Number of length n+2 0..8 arrays with no three unequal elements in a row and new values 0..8 introduced in 0..8 order.
4, 9, 21, 51, 127, 324, 844, 2243, 6073, 16737, 46905, 133556, 386062, 1132107, 3365627, 10137558, 30920924, 95456942, 298125982, 941555265, 3005897555, 9696696210, 31596681866, 103963289341, 345299662267, 1157307776719
Offset: 1
Keywords
Examples
Some solutions for n=5 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 ..0....1....1....1....0....0....1....1....1....0....1....1....1....0....1....1 ..1....1....1....1....1....1....1....1....0....0....0....0....0....0....0....1 ..0....1....2....0....1....1....0....1....1....0....0....0....0....1....0....1 ..0....2....1....0....2....1....0....1....1....0....1....2....0....1....0....0 ..1....2....1....0....2....2....1....1....1....1....1....2....2....2....2....0 ..0....2....2....2....3....2....1....2....0....0....2....1....2....1....0....1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 15*a(n-1) -76*a(n-2) +78*a(n-3) +554*a(n-4) -1518*a(n-5) -1000*a(n-6) +6492*a(n-7) -505*a(n-8) -13105*a(n-9) +2036*a(n-10) +13670*a(n-11) +672*a(n-12) -5632*a(n-13) -1680*a(n-14)
Comments