# A003610 (b-file synthesized from sequence entry) 1 2 2 6 3 8 4 8 5 56 6 24 7 168 8 240 9 608 10 920 11 5680 12 6104 13 18416 14 43008 15 148152 16 325608 17 980840 18 2421096 19 7336488 20 19769312 21 58192608 22 164776248 23 502085760 24 1427051544 25 4261678656 26 12615722288 27 37914214232 28 113567513528 29 343641240328 30 1039134670952