A211575 - OEIS

A211575

Number of -2..2 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 or six distinct values for every i,j,k<=n.

24, 80, 202, 476, 1082, 2470, 5562, 12796, 29044, 67738, 155328, 366934, 849090, 2027430, 4726368, 11383748, 26693878, 64741904, 152513458, 371958154, 879391758, 2154278468, 5107665568, 12557355846, 29839686200, 73574774818

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OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..37

FORMULA

Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 46*a(n-3) + 88*a(n-4) + 49*a(n-5) - 231*a(n-6) + 82*a(n-7) + 168*a(n-8) - 100*a(n-9) - 36*a(n-10) + 24*a(n-11).

Empirical g.f.: 2*x*(12 - 32*x - 103*x^2 + 304*x^3 + 200*x^4 - 759*x^5 - 134*x^6 + 666*x^7 + 52*x^8 - 156*x^9) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 6*x^2)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Jul 19 2018

EXAMPLE

Some solutions for n=5:

.-1....1...-1....0....1...-1....1...-1...-1...-2....0....1...-1....1....0....1

..2....0...-2....2....1....2....0...-2...-2...-1....1....2...-1....2....2....1

..1....1...-1....0....1....1....1...-1...-2...-2....2....1....2....1....0....0

.-2....2...-2...-2...-1....2....2...-1...-1....0...-1...-2...-1....2....2....1

.-1....0...-1....0...-1...-1....1....0...-2...-2....0...-1...-1....2....0....0

..2....1....2....2...-1....0....1...-1...-1....0....1...-2....2....1....1....1

CROSSREFS

Sequence in context: A190102 A060673 A167561 * A211583 A211589 A211597

Adjacent sequences: A211572 A211573 A211574 * A211576 A211577 A211578

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 16 2012

STATUS

approved