# A125280 (b-file synthesized from sequence entry) 0 1 1 2 2 5 3 15 4 53 5 217 6 1011 7 5260 8 30041 9 185677 10 1228209 11 8620874 12 63792445 13 495163451 14 4015888557 15 33923543492 16 297706713081 17 2708377382444 18 25495655264883 19 247952347547483 20 2487743315817023 21 25717746952124842