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A177296
Number of permutations of 3 copies of 1..n with all adjacent differences <= 6 in absolute value.
0
1, 1, 20, 1680, 369600, 168168000, 137225088000, 182509367040000, 156952841101056000, 96333779412718848000
OFFSET
0,3
COMMENTS
a(n) = (3n)!/6^n for n<=7.
CROSSREFS
Cf. A014606.
Sequence in context: A177616 A177295 A177635 * A177297 A014606 A330196
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 06 2010
STATUS
approved