# A012592 (b-file synthesized from sequence entry) 0 0 1 1 2 2 3 4 4 24 5 188 6 1480 7 14824 8 182784 9 2495632 10 37988128 11 649646336 12 12226037120 13 250202750016 14 5549572352896 15 132663174885760 16 3396998634659840 17 92768709569362176 18 2691992696956801536