# A006663 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 2 4 8 5 12 6 52 7 86 8 400 9 710 10 3404 11 6316 12 30888 13 59204 14 293192 15 576018 16 2877184 17 5764430 18 28967428 19 58970568 20 297634344 21 614037754 22 3109111064