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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 7 |
| 4 | 17 |
| 5 | 40 |
| 6 | 97 |
| 7 | 238 |
| 8 | 587 |
| 9 | 1458 |
| 10 | 3640 |
| 11 | 9124 |
| 12 | 22951 |
| 13 | 57904 |
| 14 | 146461 |
| 15 | 371281 |
| 16 | 943045 |
| 17 | 2399460 |
| 18 | 6114555 |
| 19 | 15603339 |
| 20 | 39866932 |
| 21 | 101976512 |
| 22 | 261117378 |
| 23 | 669239402 |
| 24 | 1716737267 |
| 25 | 4407306170 |
| 26 | 11323050897 |
| 27 | 29110603423 |
| 28 | 74888578067 |
[1,2,3,7,17,40,97,238,587,1458,3640,9124,22951, 57904,146461,371281,943045,2399460,6114555, 15603339,39866932,101976512,261117378,669239402, 1716737267,4407306170,11323050897,29110603423, 74888578067] |