OFFSET
0,3
FORMULA
a(n) = [Product_{j=0..n-1} (1-3*j)]/n! * 3^(n*(n-1)/2).
PROG
(PARI) a(n)=prod(j=0, n-1, 1-3*j)/n!*3^(n*(n-1)/2)
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Mar 14 2006
STATUS
approved