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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 28 |
| 5 | 64 |
| 6 | 173 |
| 7 | 438 |
| 8 | 1200 |
| 9 | 3325 |
| 10 | 9289 |
| 11 | 26494 |
| 12 | 76483 |
| 13 | 221530 |
| 14 | 645685 |
| 15 | 1895983 |
| 16 | 5593440 |
| 17 | 16578830 |
| 18 | 49347768 |
| 19 | 147402214 |
| 20 | 441641536 |
| 21 | 1326941536 |
| 22 | 3996900895 |
| 23 | 12066234206 |
| 24 | 36501753353 |
[0,1,4,11,28,64,173,438,1200,3325,9289,26494, 76483,221530,645685,1895983,5593440,16578830, 49347768,147402214,441641536,1326941536, 3996900895,12066234206,36501753353] |