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| n | a(n) |
|---|---|
| 1 | 28 |
| 2 | 256 |
| 3 | 1372 |
| 4 | 6527 |
| 5 | 27415 |
| 6 | 104291 |
| 7 | 363859 |
| 8 | 1173141 |
| 9 | 3539402 |
| 10 | 10055917 |
| 11 | 27072084 |
| 12 | 69433880 |
| 13 | 170442542 |
| 14 | 402042194 |
| 15 | 914489241 |
| 16 | 2012051851 |
| 17 | 4293710454 |
| 18 | 8908363984 |
| 19 | 18007433696 |
| 20 | 35530979384 |
| 21 | 68546844725 |
| 22 | 129490989279 |
| 23 | 239852605993 |
[28,256,1372,6527,27415,104291,363859,1173141, 3539402,10055917,27072084,69433880,170442542, 402042194,914489241,2012051851,4293710454, 8908363984,18007433696,35530979384,68546844725, 129490989279,239852605993] |