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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 13 |
| 5 | 47 |
| 6 | 128 |
| 7 | 405 |
| 8 | 1181 |
| 9 | 3598 |
| 10 | 10705 |
| 11 | 32259 |
| 12 | 96544 |
| 13 | 290009 |
| 14 | 869417 |
| 15 | 2609238 |
| 16 | 7826117 |
| 17 | 23480935 |
| 18 | 70438624 |
| 19 | 211322637 |
| 20 | 633956965 |
| 21 | 1901888606 |
| 22 | 5705637161 |
| 23 | 17116957851 |
| 24 | 51350798528 |
| 25 | 154052516977 |
| 26 | 462157354513 |
| 27 | 1386472381350 |
[1,1,6,13,47,128,405,1181,3598,10705,32259,96544, 290009,869417,2609238,7826117,23480935,70438624, 211322637,633956965,1901888606,5705637161, 17116957851,51350798528,154052516977,462157354513, 1386472381350] |