# A274461 (b-file synthesized from sequence entry) 0 1 1 4 2 8 3 72 4 144 5 3600 6 10800 7 21600 8 1058400 9 2116800 10 6350400 11 768398400 12 3841992000 13 7683984000 14 1298593296000 15 3895779888000 16 7791559776000 17 2251760775264000 18 15762325426848000 19 5690199479092128000 20 11380398958184256000 21 6020231048879471424000 22 30101155244397357120000 23 90303465733192071360000