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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 20 |
| 3 | 147 |
| 4 | 649 |
| 5 | 2195 |
| 6 | 6301 |
| 7 | 15601 |
| 8 | 34847 |
| 9 | 71509 |
| 10 | 137520 |
| 11 | 249799 |
| 12 | 433038 |
| 13 | 720820 |
| 14 | 1159650 |
| 15 | 1809461 |
| 16 | 2749459 |
| 17 | 4079634 |
| 18 | 5928317 |
| 19 | 8451964 |
| 20 | 11845820 |
| 21 | 16345291 |
| 22 | 22238744 |
| 23 | 29865253 |
| 24 | 39632411 |
| 25 | 52016744 |
| 26 | 67583239 |
| 27 | 86980484 |
| 28 | 110967120 |
[1,20,147,649,2195,6301,15601,34847,71509,137520, 249799,433038,720820,1159650,1809461,2749459, 4079634,5928317,8451964,11845820,16345291, 22238744,29865253,39632411,52016744,67583239, 86980484,110967120] |