# A327998 (b-file synthesized from sequence entry) 0 1 1 1 2 4 3 36 4 36 5 900 6 400 7 19600 8 4900 9 396900 10 63504 11 7683984 12 853776 13 144288144 14 11778624 15 2650190400 16 165636900 17 47869064100 18 2363904400 19 853369488400 20 34134779536 21 15053437775376 22 497634306624 23 263248548204096 24 7312459672336 25 4570287295210000 26 108172480360000