# A124675 (b-file synthesized from sequence entry) 1 1 2 2 3 6 4 8 5 120 6 12 7 5040 8 384 9 324 10 80 11 39916800 12 144 13 6227020800 14 672 15 90 16 10321920 17 355687428096000 18 2592 19 121645100408832000 20 1600 21 756 22 84480 23 25852016738884976640000 24 62208 25 9000000 26 1198080 27 14285134080 28 18816