# A115106 (b-file synthesized from sequence entry) 0 1 1 4 2 12 3 20 4 136 5 392 6 1408 7 4544 8 15040 9 48896 10 159232 11 516608 12 1675264 13 5427200 14 17575936 15 56901632 16 184188928 17 596148224 18 1929379840 19 6244007936 20 20206845952 21 65392345088 22 211617316864 23 684814499840 24 2216119238656