# A109095 (b-file synthesized from sequence entry) 1 6 2 10 3 24 4 120 5 720 6 5040 7 40320 8 362880 9 3628800 10 39916800 11 479001600 12 6227020800 13 87178291200 14 1307674368000 15 20922789888000 16 355687428096000 17 6402373705728000 18 121645100408832000 19 2432902008176640000 20 51090942171709440000 21 1124000727777607680000 22 25852016738884976640000