# A005551 (b-file synthesized from sequence entry) 4 1 5 20 6 130 7 576 8 2218 9 8170 10 29830 11 109192 12 402258 13 1492746 14 5578742 15 20986424 16 79420122 17 302175648 18 1155298598 19 4436375790 20 17103294308 21 66174208076 22 256870951048 23 1000080994758 24 3904276709604 25 15280413966512