# A138896 (b-file synthesized from sequence entry) 2 3 3 15 4 280 5 11340 6 798336 7 86486400 8 13343616000 9 2778808032000 10 750895681536000 11 255454710858547200 12 106826515449937920000 13 53858368206010368000000 14 32215590089995124736000000 15 22555515290152300904448000000 16 18272974787062050706056806400000 17 16959604724241965811558973440000000