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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 21 |
| 3 | 105 |
| 4 | 361 |
| 5 | 2045 |
| 6 | 6141 |
| 7 | 38865 |
| 8 | 104401 |
| 9 | 726245 |
| 10 | 1774821 |
| 11 | 13394745 |
| 12 | 30171961 |
| 13 | 244487885 |
| 14 | 512923341 |
| 15 | 4424729505 |
| 16 | 8719696801 |
| 17 | 79515368885 |
| 18 | 148234845621 |
| 19 | 1420480747785 |
| 20 | 2519992375561 |
| 21 | 25247684340125 |
| 22 | 42839870384541 |
[1,5,21,105,361,2045,6141,38865,104401,726245, 1774821,13394745,30171961,244487885,512923341, 4424729505,8719696801,79515368885,148234845621, 1420480747785,2519992375561,25247684340125, 42839870384541] |