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A250313 Number of length n+2 0..1 arrays with the sum of second differences squared multiplied by some arrangement of +-1 equal to zero. 1
2, 8, 8, 24, 42, 104, 212, 464, 950, 1968, 3984, 8072, 16226, 32600, 65324, 130848, 261870, 524000, 1048232, 2096792, 4193882, 8388168, 16776708, 33553904, 67108262, 134217104, 268434752, 536870184, 1073741010, 2147482808, 4294966364 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 3*a(n-4) + 3*a(n-5) - 2*a(n-6).

Empirical g.f.: 2*x*(1 + x - 8*x^2 + 6*x^3 + 6*x^4 - 2*x^5) / ((1 - x)^3*(1 + x)^2*(1 - 2*x)). - Colin Barker, Nov 12 2018

EXAMPLE

Some solutions for n=6:

..1....0....0....0....1....0....0....1....1....0....1....0....0....1....1....0

..1....0....0....1....1....0....1....1....0....0....0....1....1....0....0....0

..0....0....0....0....1....1....0....0....1....0....0....0....0....1....1....1

..0....0....1....0....0....1....1....1....0....1....1....1....0....1....1....1

..1....1....1....0....0....1....0....0....1....1....0....1....1....0....0....1

..0....0....1....0....1....1....0....0....0....1....0....1....1....0....0....0

..0....1....0....1....1....1....1....1....1....1....0....1....0....1....0....1

..0....1....0....0....1....1....0....1....0....1....1....0....1....0....1....1

CROSSREFS

Column 1 of A250320.

Sequence in context: A093907 A116471 A146749 * A180825 A230708 A230739

Adjacent sequences:  A250310 A250311 A250312 * A250314 A250315 A250316

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 18 2014

STATUS

approved

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Last modified December 15 14:37 EST 2019. Contains 329999 sequences. (Running on oeis4.)