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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 26 |
| 6 | 76 |
| 7 | 232 |
| 8 | 764 |
| 9 | 2620 |
| 10 | 9496 |
| 11 | 35696 |
| 12 | 140152 |
| 13 | 568504 |
| 14 | 2390480 |
| 15 | 10349536 |
| 16 | 46206736 |
| 17 | 211799312 |
| 18 | 997313824 |
| 19 | 4809701440 |
| 20 | 23758664096 |
| 21 | 119952692896 |
| 22 | 618884638912 |
| 23 | 3257843882624 |
| 24 | 17492190577600 |
| 25 | 95680443760576 |
| 26 | 532985208200576 |
| 27 | 3020676745975552 |
[1,1,2,4,10,26,76,232,764,2620,9496,35696,140152, 568504,2390480,10349536,46206736,211799312, 997313824,4809701440,23758664096,119952692896, 618884638912,3257843882624,17492190577600, 95680443760576,532985208200576,3020676745975552] |