Let be the Catalan's numbers defined by c(1)=1, (n+1).c(n+1)=2.(2n-1).c(n). For n>1, if (n+1) modulo 6 = 1 or 5, then (c(n) modulo (n+1))=0. Beginning of c(n) modulo (n+1), n>0: 1 1 2 0 2 0 4 6 0 0 8 0 0 10 8 0 0 0 0 0 0 0 ..... (sequence not in EOIS) Are there others n with c(n) modulo (n+1) not zero ? Claude lenormand (e-mail: hlne.lenormand at voonoo.net)