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 A221516 Number of 0..n arrays of length 5 with each element differing from at least one neighbor by 2 or more, starting with 0. 1
 0, 3, 30, 130, 381, 884, 1765, 3174, 5285, 8296, 12429, 17930, 25069, 34140, 45461, 59374, 76245, 96464, 120445, 148626, 181469, 219460, 263109, 312950, 369541, 433464, 505325, 585754, 675405, 774956, 885109, 1006590, 1140149, 1286560 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 5 of A221515. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 1*n^4 - 1*n^3 - 10*n^2 + 33*n - 34 for n>3. Conjectures from Colin Barker, Aug 06 2018: (Start) G.f.: x^2*(3 + 15*x + 10*x^2 + x^3 - 6*x^4 + 2*x^5 - x^6) / (1 - x)^5. a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>8. (End) EXAMPLE Some solutions for n=6: ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 ..3....6....3....6....4....2....3....2....5....4....4....6....2....6....6....2 ..5....2....4....2....6....3....3....0....6....1....0....0....0....4....5....3 ..4....4....6....6....5....5....0....6....0....0....5....4....4....2....1....6 ..6....6....4....4....0....3....4....1....2....5....0....2....0....4....4....0 CROSSREFS Cf. A221515. Sequence in context: A100259 A031205 A225018 * A174774 A020874 A161806 Adjacent sequences:  A221513 A221514 A221515 * A221517 A221518 A221519 KEYWORD nonn AUTHOR R. H. Hardin, Jan 18 2013 STATUS approved

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Last modified January 19 20:41 EST 2020. Contains 331066 sequences. (Running on oeis4.)