OFFSET
1,2
COMMENTS
a(n) is the number of odd permutations, pi(0),...,pi(2*n), of 0,...,2*n such that pi(0) = 0 and p(k) = k + pi(k) (mod 2*n+1), k=0,...,2*n is also a permutation of 0,...,2*n. - Sean A. Irvine, Jan 31 2015
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
D. H. Lehmer, Some properties of circulants, J. Number Theory 5 (1973), 43-54.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
Name clarified and offset corrected by Sean A. Irvine, Jan 31 2015
a(8)-a(9) from Sean A. Irvine, Jan 31 2015
STATUS
approved