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A177288 Number of permutations of 2 copies of 1..n with all adjacent differences <= 7 in absolute value. 0
1, 6, 90, 2520, 113400, 7484400, 681080400, 81729648000, 7580424852000, 569159625434400, 36636506215016400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n)=(2n)!/2^n for n<=8

LINKS

Table of n, a(n) for n=1..11.

CROSSREFS

Sequence in context: A177286 A177594 A177287 * A177289 A177290 A000680

Adjacent sequences:  A177285 A177286 A177287 * A177289 A177290 A177291

KEYWORD

nonn

AUTHOR

R. H. Hardin May 06 2010

STATUS

approved

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Last modified February 24 21:22 EST 2018. Contains 299628 sequences. (Running on oeis4.)