# A005550 (b-file synthesized from sequence entry) 3 3 4 16 5 57 6 184 7 601 8 2036 9 7072 10 25088 11 90503 12 330836 13 1222783 14 4561058 15 17145990 16 64888020 17 246995400 18 944986464 19 3631770111 20 14013725268 21 54268946152 22 210842757798 23 821569514032 24 3209925357702 25 12572219405144