# A020097 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 4 4 13 5 61 6 346 7 2326 8 17973 9 156849 10 1525708 11 16366685 12 191936577 13 2442829157 14 33533382056 15 493855262997 16 7766996408942 17 129920667204110 18 2303139100436493 19 43131514062719763 20 850867141055471684