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 A208403 Number of n X 3 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors. 1
 5, 182, 10682, 667478, 42012698, 2646531062, 166729574522, 10503950018198, 661748758909658, 41690171165650742, 2626480778916392762, 165468289040095516118, 10424502209304556920218, 656743639184636861807222 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A208408. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 70*a(n-1) - 441*a(n-2) for n>3. Conjectures from Colin Barker, Jul 02 2018: (Start) G.f.: x*(5 - 168*x + 147*x^2) / ((1 - 7*x)*(1 - 63*x)). a(n) = (2/27)*7^(-1+n) * (27+4*9^n) for n>1. (End) EXAMPLE Some solutions for n=4: ..0..0..0....0..0..0....0..0..0....0..0..0....0..1..1....0..0..0....0..0..0 ..1..1..0....0..1..0....0..1..1....0..1..0....1..0..2....0..1..0....0..1..1 ..0..1..0....1..2..1....1..0..0....0..1..1....3..0..1....2..1..1....2..0..2 ..0..1..0....0..1..3....0..1..1....2..0..2....1..1..1....2..1..1....2..1..0 CROSSREFS Cf. A208408. Sequence in context: A345338 A256286 A304277 * A280797 A094081 A189645 Adjacent sequences:  A208400 A208401 A208402 * A208404 A208405 A208406 KEYWORD nonn AUTHOR R. H. Hardin, Feb 26 2012 STATUS approved

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Last modified August 18 21:45 EDT 2022. Contains 356215 sequences. (Running on oeis4.)