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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 13 |
| 5 | 37 |
| 6 | 120 |
| 7 | 395 |
| 8 | 1381 |
| 9 | 4931 |
| 10 | 18074 |
| 11 | 67287 |
| 12 | 254387 |
| 13 | 972559 |
| 14 | 3756315 |
| 15 | 14629237 |
| 16 | 57395490 |
| 17 | 226613217 |
| 18 | 899773355 |
| 19 | 3590349661 |
| 20 | 14390323014 |
| 21 | 57907783039 |
| 22 | 233867667197 |
| 23 | 947601928915 |
| 24 | 3851054528838 |
| 25 | 15693587686823 |
| 26 | 64114744713845 |
| 27 | 262543966114921 |
| 28 | 1077406218930902 |
[1,2,5,13,37,120,395,1381,4931,18074,67287,254387, 972559,3756315,14629237,57395490,226613217, 899773355,3590349661,14390323014,57907783039, 233867667197,947601928915,3851054528838, 15693587686823,64114744713845,262543966114921, 1077406218930902] |