# A342856 (b-file synthesized from sequence entry) 1 1 2 24 3 120 4 720 5 5040 6 40320 7 362880 8 3628800 9 39916800 10 479001600 11 6227020800 12 87178291200 13 1307674368000 14 20922789888000 15 355687428096000 16 6402373705728000 17 121645100408832000 18 2432902008176640000 19 51090942171709440000 20 1124000727777607680000