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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 23 |
| 6 | 71 |
| 7 | 229 |
| 8 | 759 |
| 9 | 2566 |
| 10 | 8817 |
| 11 | 30717 |
| 12 | 108278 |
| 13 | 385509 |
| 14 | 1384262 |
| 15 | 5006925 |
| 16 | 18225400 |
| 17 | 66711769 |
| 18 | 245400354 |
| 19 | 906711758 |
| 20 | 3363516354 |
| 21 | 12522302087 |
| 22 | 46773419089 |
| 23 | 175232388955 |
| 24 | 658295899526 |
| 25 | 2479268126762 |
| 26 | 9359152696924 |
| 27 | 35406650450001 |
| 28 | 134215036793130 |
[1,1,3,8,23,71,229,759,2566,8817,30717,108278, 385509,1384262,5006925,18225400,66711769, 245400354,906711758,3363516354,12522302087, 46773419089,175232388955,658295899526, 2479268126762,9359152696924,35406650450001, 134215036793130] |