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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 39 |
| 5 | 165 |
| 6 | 743 |
| 7 | 3507 |
| 8 | 17199 |
| 9 | 87126 |
| 10 | 454159 |
| 11 | 2430031 |
| 12 | 13326623 |
| 13 | 74856230 |
| 14 | 430628069 |
| 15 | 2538270783 |
| 16 | 15343363603 |
| 17 | 95233568052 |
| 18 | 607850790015 |
| 19 | 3996223189468 |
| 20 | 27105153736781 |
| 21 | 189947851239185 |
| 22 | 1376864409041417 |
| 23 | 10330672337146804 |
| 24 | 80248762443834399 |
| 25 | 645206035074873681 |
[1,1,3,10,39,165,743,3507,17199,87126,454159, 2430031,13326623,74856230,430628069,2538270783, 15343363603,95233568052,607850790015, 3996223189468,27105153736781,189947851239185, 1376864409041417,10330672337146804, 80248762443834399,645206035074873681] |