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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 23 |
| 5 | 76 |
| 6 | 231 |
| 7 | 681 |
| 8 | 1968 |
| 9 | 5605 |
| 10 | 15817 |
| 11 | 44324 |
| 12 | 123573 |
| 13 | 343157 |
| 14 | 950000 |
| 15 | 2623530 |
| 16 | 7230746 |
| 17 | 19896140 |
| 18 | 54671729 |
| 19 | 150058028 |
| 20 | 411465352 |
| 21 | 1127315946 |
| 22 | 3086355718 |
| 23 | 8444524052 |
| 24 | 23092305853 |
| 25 | 63117665557 |
| 26 | 172444844373 |
| 27 | 470961842866 |
| 28 | 1285804853026 |
| 29 | 3509404275438 |
| 30 | 9575773901601 |
[0,1,6,23,76,231,681,1968,5605,15817,44324,123573, 343157,950000,2623530,7230746,19896140,54671729, 150058028,411465352,1127315946,3086355718, 8444524052,23092305853,63117665557,172444844373, 470961842866,1285804853026,3509404275438, 9575773901601] |