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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 1 |
| 3 | 6 |
| 4 | 10 |
| 5 | 13 |
| 6 | 38 |
| 7 | 73 |
| 8 | 164 |
| 9 | 351 |
| 10 | 749 |
| 11 | 1719 |
| 12 | 3710 |
| 13 | 8182 |
| 14 | 18453 |
| 15 | 40666 |
| 16 | 90453 |
| 17 | 201921 |
| 18 | 448575 |
| 19 | 999776 |
| 20 | 2226884 |
| 21 | 4957665 |
| 22 | 11048840 |
| 23 | 24608791 |
| 24 | 54816139 |
| 25 | 122135777 |
| 26 | 272069268 |
| 27 | 606114434 |
| 28 | 1350348321 |
| 29 | 3008242832 |
| 30 | 6701882069 |
| 31 | 14930628603 |
[2,1,6,10,13,38,73,164,351,749,1719,3710,8182, 18453,40666,90453,201921,448575,999776,2226884, 4957665,11048840,24608791,54816139,122135777, 272069268,606114434,1350348321,3008242832, 6701882069,14930628603] |