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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 71 |
| 6 | 260 |
| 7 | 971 |
| 8 | 3670 |
| 9 | 13968 |
| 10 | 53369 |
| 11 | 204352 |
| 12 | 783408 |
| 13 | 3005284 |
| 14 | 11533014 |
| 15 | 44267854 |
| 16 | 169935041 |
| 17 | 652385639 |
| 18 | 2504613713 |
| 19 | 9615798516 |
| 20 | 36917689075 |
| 21 | 141737959416 |
| 22 | 544175811783 |
| 23 | 2089262741393 |
| 24 | 8021347093432 |
| 25 | 30796530585417 |
| 26 | 118237818141689 |
| 27 | 453953210838465 |
[1,2,6,20,71,260,971,3670,13968,53369,204352, 783408,3005284,11533014,44267854,169935041, 652385639,2504613713,9615798516,36917689075, 141737959416,544175811783,2089262741393, 8021347093432,30796530585417,118237818141689, 453953210838465] |