# A027853 (b-file synthesized from sequence entry) 0 0 1 1 2 4 3 15 4 52 5 175 6 571 7 1838 8 5834 9 18363 10 57372 11 178271 12 551344 13 1698782 14 5217266 15 15979465 16 48825416 17 148877730 18 453124341 19 1376890744 20 4177819301 21 12659943750 22 38317731349 23 115851225052 24 349924919167