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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 4 |
| 4 | 19 |
| 5 | 0 |
| 6 | 84 |
| 7 | 212 |
| 8 | 1366 |
| 9 | 1302 |
| 10 | 11152 |
| 11 | 21206 |
| 12 | 132937 |
| 13 | 213292 |
| 14 | 1337380 |
| 15 | 2647514 |
| 16 | 15028233 |
| 17 | 29622012 |
| 18 | 163019148 |
| 19 | 347100284 |
| 20 | 1830194472 |
| 21 | 3971385578 |
| 22 | 20474549872 |
| 23 | 45912542370 |
| 24 | 231923364114 |
| 25 | 527948983676 |
| 26 | 2633446191848 |
| 27 | 6087316332422 |
[0,0,4,19,0,84,212,1366,1302,11152,21206,132937, 213292,1337380,2647514,15028233,29622012, 163019148,347100284,1830194472,3971385578, 20474549872,45912542370,231923364114,527948983676, 2633446191848,6087316332422] |