# A052655 (b-file synthesized from sequence entry) 0 0 1 1 2 6 3 18 4 96 5 600 6 4320 7 35280 8 322560 9 3265920 10 36288000 11 439084800 12 5748019200 13 80951270400 14 1220496076800 15 19615115520000 16 334764638208000 17 6046686277632000 18 115242726703104000 19 2311256907767808000