# A072346 (b-file synthesized from sequence entry) 0 1 1 1 2 1 3 3 4 2 5 15 6 6 7 105 8 24 9 945 10 120 11 10395 12 720 13 135135 14 5040 15 2027025 16 40320 17 34459425 18 362880 19 654729075 20 3628800 21 13749310575 22 39916800 23 316234143225 24 479001600 25 7905853580625 26 6227020800 27 213458046676875 28 87178291200 29 6190283353629375 30 1307674368000