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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 21 |
| 3 | 58 |
| 4 | 144 |
| 5 | 342 |
| 6 | 795 |
| 7 | 1818 |
| 8 | 4095 |
| 9 | 9104 |
| 10 | 20028 |
| 11 | 43692 |
| 12 | 94661 |
| 13 | 203886 |
| 14 | 436905 |
| 15 | 932070 |
| 16 | 1980648 |
| 17 | 4194306 |
| 18 | 8854639 |
| 19 | 18641346 |
| 20 | 39146835 |
| 21 | 82021948 |
| 22 | 171500436 |
| 23 | 357913944 |
| 24 | 745654041 |
| 25 | 1550960406 |
| 26 | 3221225469 |
| 27 | 6681060242 |
| 28 | 13839339072 |
| 29 | 28633115310 |
| 30 | 59175104963 |
| 31 | 122167958634 |
[1,6,21,58,144,342,795,1818,4095,9104,20028,43692, 94661,203886,436905,932070,1980648,4194306, 8854639,18641346,39146835,82021948,171500436, 357913944,745654041,1550960406,3221225469, 6681060242,13839339072,28633115310,59175104963, 122167958634] |