# A006841 (b-file synthesized from sequence entry) 1 1 2 1 3 1 4 2 5 4 6 10 7 28 8 127 9 686 10 4975 11 42529 12 420948 13 4622509 14 55670332 15 726738971 16 10217376792 17 153848448652 18 2470073249960 19 42120966152815 20 760282326662191 21 14481561464994821 22 290289454462745374 23 6108699653117045614