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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.)