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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 18 |
| 3 | 68 |
| 4 | 253 |
| 5 | 945 |
| 6 | 3526 |
| 7 | 13160 |
| 8 | 49113 |
| 9 | 183293 |
| 10 | 684058 |
| 11 | 2552940 |
| 12 | 9527701 |
| 13 | 35557865 |
| 14 | 132703758 |
| 15 | 495257168 |
| 16 | 1848324913 |
| 17 | 6898042485 |
| 18 | 25743845026 |
| 19 | 96077337620 |
| 20 | 358565505453 |
| 21 | 1338184684193 |
| 22 | 4994173231318 |
| 23 | 18638508241080 |
[1,5,18,68,253,945,3526,13160,49113,183293,684058, 2552940,9527701,35557865,132703758,495257168, 1848324913,6898042485,25743845026,96077337620, 358565505453,1338184684193,4994173231318, 18638508241080] |