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| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 13 |
| 2 | 57 |
| 3 | 250 |
| 4 | 1097 |
| 5 | 4814 |
| 6 | 21126 |
| 7 | 92711 |
| 8 | 406861 |
| 9 | 1785505 |
| 10 | 7835669 |
| 11 | 34386747 |
| 12 | 150905861 |
| 13 | 662248712 |
| 14 | 2906271193 |
| 15 | 12754139184 |
| 16 | 55971399613 |
| 17 | 245629871954 |
| 18 | 1077943993063 |
| 19 | 4730545364606 |
| 20 | 20759946333583 |
| 21 | 91104796287932 |
| 22 | 399812397069577 |
| 23 | 1754572309731352 |
[3,13,57,250,1097,4814,21126,92711,406861,1785505, 7835669,34386747,150905861,662248712,2906271193, 12754139184,55971399613,245629871954, 1077943993063,4730545364606,20759946333583, 91104796287932,399812397069577,1754572309731352] |