# A007999 (b-file synthesized from sequence entry) 0 1 1 1 2 1 3 1 4 2 5 3 6 8 7 19 8 64 9 213 10 880 11 3717 12 18288 13 92935 14 531440 15 3147495 16 20525168 17 138638825 18 1015694832 19 7700244745 20 62623847536 21 526317901451 22 4705365925872 23 43407723925499 24 423149546210416 25 4250149857500861 26 44868038386273776 27 487341646372204813