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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 27 |
| 3 | 101 |
| 4 | 357 |
| 5 | 1215 |
| 6 | 4043 |
| 7 | 13239 |
| 8 | 42849 |
| 9 | 137446 |
| 10 | 437775 |
| 11 | 1386369 |
| 12 | 4369661 |
| 13 | 13717842 |
| 14 | 42918903 |
| 15 | 133887207 |
| 16 | 416601657 |
| 17 | 1293386940 |
| 18 | 4007492727 |
| 19 | 12395015289 |
| 20 | 38276340453 |
| 21 | 118029405441 |
| 22 | 363483388935 |
| 23 | 1118056644207 |
| 24 | 3435356994857 |
| 25 | 10545018480000 |
| 26 | 32338826982603 |
[1,6,27,101,357,1215,4043,13239,42849,137446, 437775,1386369,4369661,13717842,42918903, 133887207,416601657,1293386940,4007492727, 12395015289,38276340453,118029405441,363483388935, 1118056644207,3435356994857,10545018480000, 32338826982603] |