# A215678 (b-file synthesized from sequence entry) 0 1 1 0 2 0 3 3 4 0 5 20 6 90 7 203 8 3360 9 11640 10 123480 11 971883 12 7155720 13 81842540 14 689969280 15 8098733243 16 87787889280 17 1037050927920 18 13312247451840 19 170378180195283 20 2401844355066240 21 34222349644158980 22 518547579965036160 23 8138997539240165003 24 132773771778775670400