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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 34 |
| 4 | 116 |
| 5 | 438 |
| 6 | 1606 |
| 7 | 6002 |
| 8 | 22548 |
| 9 | 85342 |
| 10 | 324716 |
| 11 | 1241166 |
| 12 | 4762000 |
| 13 | 18329054 |
| 14 | 70742790 |
| 15 | 273689362 |
| 16 | 1061055812 |
| 17 | 4121135838 |
| 18 | 16032654628 |
| 19 | 62463904958 |
| 20 | 243682621224 |
| 21 | 951781620022 |
| 22 | 3721520393036 |
| 23 | 14565753339054 |
| 24 | 57060974849656 |
| 25 | 223721451300518 |
| 26 | 877830004120296 |
[1,2,6,34,116,438,1606,6002,22548,85342,324716, 1241166,4762000,18329054,70742790,273689362, 1061055812,4121135838,16032654628,62463904958, 243682621224,951781620022,3721520393036, 14565753339054,57060974849656,223721451300518, 877830004120296] |