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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 28 |
| 5 | 86 |
| 6 | 315 |
| 7 | 1050 |
| 8 | 3938 |
| 9 | 13753 |
| 10 | 52320 |
| 11 | 188061 |
| 12 | 722193 |
| 13 | 2646052 |
| 14 | 10228879 |
| 15 | 37987092 |
| 16 | 147565862 |
| 17 | 553507453 |
| 18 | 2158209505 |
| 19 | 8157286661 |
| 20 | 31899928604 |
| 21 | 121298012320 |
| 22 | 475469386593 |
| 23 | 1816745698379 |
| 24 | 7135157076541 |
| 25 | 27372220437363 |
| 26 | 107676261271480 |
| 27 | 414456446406897 |
| 28 | 1632603868509047 |
[1,1,3,8,28,86,315,1050,3938,13753,52320,188061, 722193,2646052,10228879,37987092,147565862, 553507453,2158209505,8157286661,31899928604, 121298012320,475469386593,1816745698379, 7135157076541,27372220437363,107676261271480, 414456446406897,1632603868509047] |