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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 23 |
| 3 | 131 |
| 4 | 664 |
| 5 | 3166 |
| 6 | 14545 |
| 7 | 65187 |
| 8 | 287060 |
| 9 | 1247690 |
| 10 | 5368670 |
| 11 | 22917198 |
| 12 | 97195968 |
| 13 | 410030812 |
| 14 | 1722027973 |
| 15 | 7204620067 |
| 16 | 30044212828 |
| 17 | 124932768082 |
| 18 | 518215690018 |
| 19 | 2144815618522 |
| 20 | 8859729437488 |
| 21 | 36533517261412 |
| 22 | 150410878895818 |
| 23 | 618371102344846 |
| 24 | 2538971850705064 |
| 25 | 10412490129563556 |
[0,3,23,131,664,3166,14545,65187,287060,1247690, 5368670,22917198,97195968,410030812,1722027973, 7204620067,30044212828,124932768082,518215690018, 2144815618522,8859729437488,36533517261412, 150410878895818,618371102344846,2538971850705064, 10412490129563556] |