rhhardin at att.net schrieb: > added a(12) > 1 0 0 8 21 0 0 3040 20505 0 0 10567748 I can confirm this. And a(13) = 103372655 (Computed with the dancing links algorithm suggested by D. E. Knuth) http://en.wikipedia.org/wiki/Dancing_Links %S A108235 1,0,0,8,21,0,0,3040,20505,0,0,10567748,103372655,0,0 Alois