OFFSET
1,5
PROG
(PARI) {a(n)=sum(j=1, n, prod(i=0, n+j-1, matrix(n+j-1, n+j-1, r, c, if(r>=c, if((r+n+j-1-i)%(c+n+j-1-i)==0, moebius((r+n+j-1-i)/(c+n+j-1-i)), 0))))[n, j])}
CROSSREFS
KEYWORD
sign
AUTHOR
Wouter Meeussen and Paul D. Hanna, Mar 05 2006
STATUS
approved