# A056352 (b-file synthesized from sequence entry) 1 0 2 0 3 0 4 0 5 0 6 60 7 1080 8 11970 9 105840 10 821952 11 5874480 12 39713490 13 258136200 14 1631272140 15 10096734312 16 61536365730 17 370710950400 18 2213749552980 19 13132080672480 20 77509456122366 21 455754569691600