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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 102 |
| 6 | 397 |
| 7 | 1500 |
| 8 | 6009 |
| 9 | 24451 |
| 10 | 101183 |
| 11 | 425673 |
| 12 | 1816275 |
| 13 | 7816634 |
| 14 | 34052901 |
| 15 | 149363641 |
| 16 | 660504469 |
| 17 | 2940315586 |
| 18 | 13164619889 |
| 19 | 59271046961 |
| 20 | 268144561326 |
| 21 | 1218435897550 |
| 22 | 5559533877874 |
| 23 | 25460075683483 |
| 24 | 117000817561805 |
| 25 | 539378629640900 |
| 26 | 2493853152959533 |
| 27 | 11562252045813059 |
| 28 | 53742395325404286 |
[1,1,3,9,30,102,397,1500,6009,24451,101183,425673, 1816275,7816634,34052901,149363641,660504469, 2940315586,13164619889,59271046961,268144561326, 1218435897550,5559533877874,25460075683483, 117000817561805,539378629640900,2493853152959533, 11562252045813059,53742395325404286] |