# A027909 (b-file synthesized from sequence entry) 0 1 1 4 2 21 3 112 4 615 5 3432 6 19383 7 110448 8 633726 9 3656360 10 21191555 11 123286440 12 719539015 13 4210967880 14 24702429825 15 145210795200 16 855172338570 17 5044470461352 18 29799593861974 19 176268499363840 20 1043889366927771 21 6188748520285584 22 36726461258947569 23 218146172715259488 24 1296812014083995850