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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 88 |
| 5 | 332 |
| 6 | 1294 |
| 7 | 5252 |
| 8 | 21872 |
| 9 | 92888 |
| 10 | 402784 |
| 11 | 1782288 |
| 12 | 8028904 |
| 13 | 36768656 |
| 14 | 171054160 |
| 15 | 807703688 |
| 16 | 3867540736 |
| 17 | 18765870208 |
| 18 | 92212515136 |
| 19 | 458609391488 |
| 20 | 2307237770496 |
| 21 | 11736266317952 |
| 22 | 60334416641536 |
| 23 | 313342967240960 |
| 24 | 1643352523119232 |
| 25 | 8700550165605632 |
[1,2,6,23,88,332,1294,5252,21872,92888,402784, 1782288,8028904,36768656,171054160,807703688, 3867540736,18765870208,92212515136,458609391488, 2307237770496,11736266317952,60334416641536, 313342967240960,1643352523119232,8700550165605632] |