# A173279 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 1 4 6 5 1 6 24 7 2 8 1 9 120 10 6 11 1 12 720 13 24 14 2 15 1 16 5040 17 120 18 6 19 1 20 40320 21 720 22 24 23 2 24 1 25 362880 26 5040 27 120 28 6 29 1 30 3628800 31 40320 32 720 33 24 34 2 35 1 36 39916800 37 362880 38 5040 39 120 40 6 41 1 42 479001600 43 3628800 44 40320 45 720 46 24 47 2 48 1 49 6227020800 50 39916800 51 362880 52 5040 53 120 54 6 55 1 56 87178291200