# A052745 (b-file synthesized from sequence entry) 0 0 1 0 2 0 3 6 4 24 5 110 6 600 7 3836 8 28224 9 235224 10 2191680 11 22584672 12 255087360 13 3134139840 14 41620400640 15 594082771200 16 9070900715520 17 147531542054400 18 2546434166169600 19 46489412442009600 20 895079522340864000 21 18125736166340812800 22 385129713617510400000