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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 33 |
| 6 | 111 |
| 7 | 378 |
| 8 | 1303 |
| 9 | 4539 |
| 10 | 15961 |
| 11 | 56598 |
| 12 | 202214 |
| 13 | 727389 |
| 14 | 2632605 |
| 15 | 9581211 |
| 16 | 35047098 |
| 17 | 128791323 |
| 18 | 475281921 |
| 19 | 1760726808 |
| 20 | 6545921136 |
| 21 | 24415415001 |
| 22 | 91340016081 |
| 23 | 342658850427 |
| 24 | 1288774386909 |
| 25 | 4858753673655 |
| 26 | 18358309669651 |
[0,1,3,10,33,111,378,1303,4539,15961,56598,202214, 727389,2632605,9581211,35047098,128791323, 475281921,1760726808,6545921136,24415415001, 91340016081,342658850427,1288774386909, 4858753673655,18358309669651] |