# A218679 (b-file synthesized from sequence entry) 0 1 1 1 2 5 3 31 4 273 5 2652 6 30071 7 375628 8 5135649 9 75945388 10 1202006514 11 20243446719 12 360517872287 13 6758311053521 14 132833835618576 15 2728019848249377 16 58370987166092073 17 1297916560174624569 18 29924140267551540116 19 713934350929955200551 20 17594768127940813003452