|
|
A177293
|
|
Number of permutations of 3 copies of 1..n with all adjacent differences <= 3 in absolute value.
|
|
0
|
|
|
1, 1, 20, 1680, 369600, 37850400, 2626916040, 171548183912, 12520880883034, 920942694050320, 65368388837752640
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
a(n) = (3n)!/6^n for n<=4.
|
|
LINKS
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|