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 A256817 Number of length n+2 0..1 arrays with at most two downsteps in every n consecutive neighbor pairs. 1
 8, 16, 32, 64, 124, 229, 402, 673, 1080, 1670, 2500, 3638, 5164, 7171, 9766, 13071, 17224, 22380, 28712, 36412, 45692, 56785, 69946, 85453, 103608, 124738, 149196, 177362, 209644, 246479, 288334, 335707, 389128, 449160, 516400, 591480, 675068 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 2 of A256816. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (1/120)*n^5 + (1/24)*n^4 + (3/8)*n^3 - (1/24)*n^2 + (277/60)*n + 3. Empirical g.f.: x*(8 - 32*x + 56*x^2 - 48*x^3 + 20*x^4 - 3*x^5) / (1 - x)^6. - Colin Barker, Jan 21 2018 EXAMPLE Some solutions for n=4: ..0....0....1....0....0....0....1....1....0....0....1....0....0....1....0....0 ..0....0....1....0....0....1....0....1....1....0....0....1....1....1....0....1 ..0....1....1....1....1....0....0....1....0....0....0....0....1....0....0....0 ..0....0....1....0....0....0....1....0....1....1....0....1....0....0....0....0 ..0....1....0....0....0....1....1....0....1....0....1....0....1....0....0....1 ..1....1....0....1....0....1....1....0....0....1....1....1....1....0....0....0 CROSSREFS Cf. A256816. Sequence in context: A054743 A192135 A345053 * A281016 A048169 A089882 Adjacent sequences: A256814 A256815 A256816 * A256818 A256819 A256820 KEYWORD nonn AUTHOR R. H. Hardin, Apr 10 2015 STATUS approved

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Last modified August 6 18:55 EDT 2024. Contains 374981 sequences. (Running on oeis4.)