# A067057 (b-file synthesized from sequence entry) 1 0 2 2 3 22 4 140 5 680 6 2800 7 10304 8 34944 9 111360 10 337920 11 985600 12 2782208 13 7641088 14 20500480 15 53903360 16 139264000 17 354287616 18 889061376 19 2203975680 20 5404098560 21 13120307200 22 31569477632 23 75342282752 24 178467635200 25 419849830400