# A105871 (b-file synthesized from sequence entry) 0 1 1 2 2 6 3 22 4 85 5 336 6 1350 7 5492 8 22554 9 93300 10 388201 11 1622868 12 6811056 13 28680356 14 121111440 15 512684484 16 2174928031 17 9243973062 18 39354962345 19 167799259130 20 716414975613 21 3062437147352 22 13105366936465 23 56139506687280