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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 37 |
| 4 | 150 |
| 5 | 654 |
| 6 | 3012 |
| 7 | 14445 |
| 8 | 71398 |
| 9 | 361114 |
| 10 | 1859628 |
| 11 | 9716194 |
| 12 | 51373180 |
| 13 | 274352316 |
| 14 | 1477635912 |
| 15 | 8016865533 |
| 16 | 43773564294 |
| 17 | 240356635170 |
| 18 | 1326359740956 |
| 19 | 7351846397334 |
| 20 | 40913414754324 |
| 21 | 228508350629892 |
[1,3,10,37,150,654,3012,14445,71398,361114, 1859628,9716194,51373180,274352316,1477635912, 8016865533,43773564294,240356635170,1326359740956, 7351846397334,40913414754324,228508350629892] |