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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 75 |
| 6 | 248 |
| 7 | 735 |
| 8 | 1952 |
| 9 | 4697 |
| 10 | 10378 |
| 11 | 21320 |
| 12 | 41163 |
| 13 | 75363 |
| 14 | 131808 |
| 15 | 221561 |
| 16 | 359742 |
| 17 | 566561 |
| 18 | 868514 |
| 19 | 1299754 |
| 20 | 1903649 |
| 21 | 2734539 |
| 22 | 3859704 |
| 23 | 5361555 |
| 24 | 7340060 |
| 25 | 9915417 |
| 26 | 13230986 |
| 27 | 17456492 |
| 28 | 22791511 |
| 29 | 29469251 |
| 30 | 37760640 |
[1,2,6,21,75,248,735,1952,4697,10378,21320,41163, 75363,131808,221561,359742,566561,868514,1299754, 1903649,2734539,3859704,5361555,7340060,9915417, 13230986,17456492,22791511,29469251,37760640] |