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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 14 |
| 4 | 40 |
| 5 | 126 |
| 6 | 408 |
| 7 | 1332 |
| 8 | 4473 |
| 9 | 15377 |
| 10 | 53627 |
| 11 | 189724 |
| 12 | 680475 |
| 13 | 2467975 |
| 14 | 9038578 |
| 15 | 33399571 |
| 16 | 124400702 |
| 17 | 466619283 |
| 18 | 1761467038 |
| 19 | 6688059913 |
| 20 | 25527326897 |
| 21 | 97901917060 |
| 22 | 377123873505 |
| 23 | 1458573962761 |
| 24 | 5662223702216 |
| 25 | 22056563938599 |
[1,1,5,14,40,126,408,1332,4473,15377,53627,189724, 680475,2467975,9038578,33399571,124400702, 466619283,1761467038,6688059913,25527326897, 97901917060,377123873505,1458573962761, 5662223702216,22056563938599] |