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A225346 Number of 6Xn -1,1 arrays such that the sum over i=1..6,j=1..n of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute n-across galley oarsmen left-right at 6 fore-aft positions so that there are no turning moments on the ship) 1
0, 15, 0, 107, 0, 397, 0, 1081, 0, 2399, 0, 4675, 0, 8273, 0, 13641, 0, 21267, 0, 31731, 0, 45637, 0, 63697, 0, 86635, 0, 115291, 0, 150513, 0, 193269, 0, 244527, 0, 305383, 0, 376929, 0, 460389, 0, 556975, 0, 668043, 0, 794921, 0, 939097, 0, 1102023, 0, 1285311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 6 of A225345

LINKS

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

FORMULA

Empirical: a(n) = a(n-2) +2*a(n-4) -a(n-6) -2*a(n-8) +a(n-12) -a(n-14) +2*a(n-18) +a(n-20) -2*a(n-22) -a(n-24) +a(n-26)

EXAMPLE

Some solutions for n=4

.-1..1..1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1..1..1...-1..1..1..1

.-1.-1.-1..1...-1..1..1..1....1..1..1..1...-1.-1..1..1...-1.-1.-1.-1

.-1.-1.-1..1....1..1..1..1...-1.-1.-1..1....1..1..1..1...-1.-1.-1..1

..1..1..1..1...-1.-1.-1..1...-1.-1.-1.-1...-1.-1.-1.-1....1..1..1..1

.-1.-1.-1.-1....1..1..1..1...-1.-1.-1..1...-1.-1.-1.-1....1..1..1..1

.-1..1..1..1...-1.-1.-1.-1....1..1..1..1....1..1..1..1...-1.-1.-1.-1

CROSSREFS

Sequence in context: A054670 A277929 A303231 * A225312 A333845 A015908

Adjacent sequences:  A225343 A225344 A225345 * A225347 A225348 A225349

KEYWORD

nonn

AUTHOR

R. H. Hardin May 05 2013

STATUS

approved

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Last modified May 18 23:31 EDT 2022. Contains 353826 sequences. (Running on oeis4.)