# A268601 (b-file synthesized from sequence entry) 0 0 1 0 2 2 3 8 4 34 5 120 6 468 7 1680 8 6530 9 23960 10 93532 11 348656 12 1366260 13 5149872 14 20238696 15 76907808 16 302903874 17 1158168792 18 4569270156 19 17555689008 20 69356428284 21 267518448912 22 1058057586456 23 4094231982048 24 16208177203764 25 62887835652720 26 249156625186328 27 968943740083040 28 3841488520364200 29 14968574892499040 30 59379627044952528