# A136591 (b-file synthesized from sequence entry) 1 1 2 1 3 -4 4 6 5 24 6 -240 7 720 8 5040 9 -80640 10 362880 11 3628800 12 -79833600 13 479001600 14 6227020800 15 -174356582400 16 1307674368000 17 20922789888000 18 -711374856192000 19 6402373705728000 20 121645100408832000 21 -4865804016353280000 22 51090942171709440000