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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 84 |
| 5 | 505 |
| 6 | 3121 |
| 7 | 20180 |
| 8 | 133604 |
| 9 | 904512 |
| 10 | 6224305 |
| 11 | 43432093 |
| 12 | 306524670 |
| 13 | 2184389874 |
| 14 | 15695947669 |
| 15 | 113595885023 |
| 16 | 827299204132 |
| 17 | 6058526521135 |
| 18 | 44586954104578 |
| 19 | 329579179316696 |
| 20 | 2445858862779018 |
| 21 | 18216235711289695 |
| 22 | 136113075865844577 |
| 23 | 1020074492384232296 |
[0,1,3,16,84,505,3121,20180,133604,904512,6224305, 43432093,306524670,2184389874,15695947669, 113595885023,827299204132,6058526521135, 44586954104578,329579179316696,2445858862779018, 18216235711289695,136113075865844577, 1020074492384232296] |