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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 13 |
| 4 | 84 |
| 5 | 181 |
| 6 | 1170 |
| 7 | 2521 |
| 8 | 16296 |
| 9 | 35113 |
| 10 | 226974 |
| 11 | 489061 |
| 12 | 3161340 |
| 13 | 6811741 |
| 14 | 44031786 |
| 15 | 94875313 |
| 16 | 613283664 |
| 17 | 1321442641 |
| 18 | 8541939510 |
| 19 | 18405321661 |
| 20 | 118973869476 |
| 21 | 256353060613 |
| 22 | 1657092233154 |
| 23 | 3570537526921 |
| 24 | 23080317394680 |
| 25 | 49731172316281 |
| 26 | 321467351292366 |
[0,1,6,13,84,181,1170,2521,16296,35113,226974, 489061,3161340,6811741,44031786,94875313, 613283664,1321442641,8541939510,18405321661, 118973869476,256353060613,1657092233154, 3570537526921,23080317394680,49731172316281, 321467351292366] |