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 A268452 Number of length-n 0..3 arrays with no adjacent pair x,x+1 followed at any distance by x+1,x. 1
 4, 16, 61, 229, 852, 3146, 11536, 42032, 152254, 548568, 1966757, 7019311, 24946486, 88313632, 311507619, 1095064315, 3837407016, 13407618832, 46715533678, 162345449332, 562801287366, 1946559269050, 6717910370343, 23136984979001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A268457. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 19*a(n-1) -156*a(n-2) +730*a(n-3) -2178*a(n-4) +4446*a(n-5) -6613*a(n-6) +7587*a(n-7) -6948*a(n-8) +5152*a(n-9) -3101*a(n-10) +1503*a(n-11) -573*a(n-12) +163*a(n-13) -31*a(n-14) +3*a(n-15) EXAMPLE Some solutions for n=9 ..0....1....0....1....1....0....3....3....3....2....1....1....2....1....0....2 ..1....2....2....0....1....1....0....2....0....2....0....0....0....2....0....2 ..2....3....2....2....0....3....3....3....3....3....0....3....0....2....0....2 ..3....0....0....2....2....0....0....3....3....0....2....3....1....0....2....2 ..1....2....1....3....0....0....1....1....1....0....0....3....2....0....0....3 ..3....3....3....3....0....2....3....3....1....1....1....1....2....3....0....1 ..1....3....0....0....2....1....1....1....0....3....1....3....2....0....1....2 ..2....0....0....2....0....1....1....1....0....3....3....1....3....0....2....0 ..0....3....2....2....0....2....2....3....0....0....0....0....0....3....3....1 CROSSREFS Cf. A268457. Sequence in context: A203153 A126929 A338531 * A133161 A103820 A206570 Adjacent sequences:  A268449 A268450 A268451 * A268453 A268454 A268455 KEYWORD nonn AUTHOR R. H. Hardin, Feb 04 2016 STATUS approved

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Last modified May 18 09:37 EDT 2022. Contains 353785 sequences. (Running on oeis4.)