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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 203 |
| 7 | 877 |
| 8 | 4140 |
| 9 | 21147 |
| 10 | 115974 |
| 11 | 678310 |
| 12 | 4205230 |
| 13 | 27497463 |
| 14 | 188884702 |
| 15 | 1358500111 |
| 16 | 10201272170 |
| 17 | 79783911418 |
| 18 | 648489059992 |
| 19 | 5467348769587 |
| 20 | 47728811273817 |
| 21 | 430751210469094 |
| 22 | 4013169321694153 |
| 23 | 38547034091725550 |
| 24 | 381252702363363969 |
[1,1,2,5,15,52,203,877,4140,21147,115974,678310, 4205230,27497463,188884702,1358500111,10201272170, 79783911418,648489059992,5467348769587, 47728811273817,430751210469094,4013169321694153, 38547034091725550,381252702363363969] |