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A177290 Number of permutations of 2 copies of 1..n with all adjacent differences <= 9 in absolute value. 0
1, 1, 6, 90, 2520, 113400, 7484400, 681080400, 81729648000, 12504636144000, 2375880867360000, 367786358267328000, 47683626117839712000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..12.

FORMULA

a(n) = (2n)!/2^n for n<=10.

CROSSREFS

Cf. A000680.

Sequence in context: A177287 A177288 A177289 * A000680 A013297 A232979

Adjacent sequences: A177287 A177288 A177289 * A177291 A177292 A177293

KEYWORD

nonn,more

AUTHOR

R. H. Hardin, May 06 2010

EXTENSIONS

a(0)=1 prepended and a(12) added by Alois P. Heinz, Jan 05 2022

STATUS

approved

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Last modified March 29 21:39 EDT 2023. Contains 361599 sequences. (Running on oeis4.)