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A211530 Number of -1..1 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having two, three, four, five or six distinct values for every i,j,k<=n. 1
8, 22, 56, 124, 270, 560, 1156, 2336, 4714, 9418, 18812, 37400, 74374, 147596, 293042, 581384, 1154070, 2290670, 4549186, 9036466, 17959458, 35705544, 71021240, 141319688, 281322224, 560223850, 1116045988, 2224048908, 4433497296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..58

FORMULA

Empirical: a(n) = 4*a(n-1) - 16*a(n-3) + 11*a(n-4) + 19*a(n-5) - 16*a(n-6) - 6*a(n-7) + 4*a(n-8).

Empirical g.f.: 2*x*(4 - 5*x - 16*x^2 + 14*x^3 + 19*x^4 - 9*x^5 - 3*x^6 + 2*x^7) / ((1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - x - 2*x^2 + x^3)). - Colin Barker, Jul 18 2018

EXAMPLE

Some solutions for n=5:

.-1....0....0...-1....1....1....1...-1....0....1....0...-1...-1...-1...-1....0

.-1....1...-1...-1...-1....0....0...-1....1....0....1....0....0...-1....1...-1

..0....0...-1....0....1....1...-1...-1....0....1...-1....1....1...-1...-1...-1

..1....1....0....1...-1...-1....0...-1....1....1...-1....0....0....1....0....0

..1...-1....1....0....0....1....1...-1....1....1...-1...-1....1....1...-1....1

..0....1....0....1....1....0....0....1....0....0...-1....0....1....1....0....1

CROSSREFS

Sequence in context: A048489 A124701 A002968 * A058404 A211479 A318034

Adjacent sequences:  A211527 A211528 A211529 * A211531 A211532 A211533

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 14 2012

STATUS

approved

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Last modified January 27 09:09 EST 2020. Contains 331293 sequences. (Running on oeis4.)