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 A245864 Number of length n+2 0..2 arrays with some pair in every consecutive three terms totalling exactly 2. 1
 19, 45, 103, 239, 553, 1281, 2967, 6873, 15921, 36881, 85435, 197911, 458463, 1062035, 2460217, 5699123, 13202089, 30582803, 70845443, 164114349, 380172929, 880675315, 2040095313, 4725906149, 10947620333, 25360298571, 58747446847 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-4) - a(n-5). Empirical g.f.: x*(19 + 7*x - 6*x^2 - 12*x^3 - 9*x^4) / ((1 - x)*(1 - x - 2*x^2 - 2*x^3 - x^4)). - Colin Barker, Nov 03 2018 EXAMPLE Some solutions for n=10: ..1....2....1....2....0....1....0....1....0....0....2....0....0....2....0....0 ..1....1....1....2....0....1....2....1....2....1....2....1....0....1....1....1 ..1....1....1....0....2....1....1....1....0....1....0....2....2....0....1....1 ..1....0....0....2....1....1....1....1....2....2....2....0....0....2....2....0 ..1....2....2....0....1....1....1....2....2....0....1....2....2....2....0....1 ..0....2....0....1....2....2....0....1....0....1....1....0....1....0....2....2 ..2....0....1....1....0....1....2....0....2....1....0....2....1....2....2....0 ..2....1....1....1....2....0....0....2....2....1....1....1....1....2....0....1 ..0....2....2....1....0....1....0....1....0....1....1....1....0....0....0....1 ..2....1....1....0....1....2....2....1....1....1....1....0....1....0....2....0 ..2....0....0....1....1....1....0....2....2....2....1....2....1....2....2....1 ..0....1....1....1....1....0....2....1....0....1....1....0....2....0....0....2 CROSSREFS Column 2 of A245869. Sequence in context: A140680 A183632 A359558 * A183624 A115249 A325451 Adjacent sequences: A245861 A245862 A245863 * A245865 A245866 A245867 KEYWORD nonn AUTHOR R. H. Hardin, Aug 04 2014 STATUS approved

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Last modified December 5 04:31 EST 2023. Contains 367574 sequences. (Running on oeis4.)