# A276230 (b-file synthesized from sequence entry) 0 1 1 2 2 4 3 12 4 36 5 144 6 720 7 3600 8 25200 9 176400 10 1587600 11 17463600 12 192099600 13 2497294800 14 32464832400 15 551902150800 16 9382336563600 17 178264394708400 18 3387023499459600 19 77901540487570800 20 1791735431214128400 21 44793385780353210000 22 1299008187630243090000