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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 33 |
| 4 | 151 |
| 5 | 647 |
| 6 | 3018 |
| 7 | 13621 |
| 8 | 64646 |
| 9 | 299168 |
| 10 | 1435690 |
| 11 | 6751801 |
| 12 | 32625433 |
| 13 | 155167697 |
| 14 | 753314009 |
| 15 | 3611917443 |
| 16 | 17596490710 |
| 17 | 84876974607 |
| 18 | 414630697985 |
| 19 | 2009149391658 |
| 20 | 9836370273415 |
| 21 | 47835367118857 |
| 22 | 234612056537696 |
| 23 | 1144260767327867 |
| 24 | 5620493553263904 |
| 25 | 27477926103350830 |
| 26 | 135139447811815770 |
[1,2,9,33,151,647,3018,13621,64646,299168,1435690, 6751801,32625433,155167697,753314009,3611917443, 17596490710,84876974607,414630697985, 2009149391658,9836370273415,47835367118857, 234612056537696,1144260767327867,5620493553263904, 27477926103350830,135139447811815770] |