OFFSET
1,2
PROG
(PARI) {a(n)=local(M=matrix(n+1, n+1, r, c, if(r>=c, polcoeff(((1-x)^2+x*O(x^n))^c, r-c))), LOG, ID=M^0); LOG=sum(m=1, n+1, -(ID-M)^m/m); -n!*LOG[n+1, 1]/2}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 21 2010
EXTENSIONS
Corrected formula by Paul D. Hanna, Jul 21 2010
STATUS
approved