|
|
A067601
|
|
a(n) is the number of inequivalent permutations of {0..2n-1}, such that the first differences (modulo 2n) are a permutation of {1..2n-1}.
|
|
3
|
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
"Inequivalent" effectively means that the permutation begins with 0 and the second item is <= n. (Working modulo 2n, s1+k,s2+k,s3+k,... is equivalent to s1,s2,s3,...; and -s1,-s2,-s3 is equivalent to s1,s2,s3,...)
The references all deal with length 12.
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
0 1 3 2 has first difference, mod 4, of 1 2 3;
0 2 1 4 5 3 has first difference, mod 6, of 2 5 3 1 4;
0 4 5 8 3 1 7 9 2 11 10 6 has first difference, mod 12, of 4 1 3 7 10 6 2 5 9 11 8.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
Eugene McDonnell (eemcd(AT)aol.com), Jan 31 2002
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|