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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 20 |
| 2 | 295 |
| 3 | 4025 |
| 4 | 54649 |
| 5 | 761166 |
| 6 | 11028590 |
| 7 | 167310220 |
| 8 | 2664929476 |
| 9 | 44601786944 |
| 10 | 784146622896 |
| 11 | 14469012689040 |
| 12 | 279870212258064 |
| 13 | 5667093514231200 |
| 14 | 119958395537083104 |
| 15 | 2650594302549806976 |
| 16 | 61049697873641191296 |
| 17 | 1463708634867162093312 |
| 18 | 36482312832434713195776 |
[1,20,295,4025,54649,761166,11028590,167310220, 2664929476,44601786944,784146622896, 14469012689040,279870212258064,5667093514231200, 119958395537083104,2650594302549806976, 61049697873641191296,1463708634867162093312, 36482312832434713195776] |