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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 9 |
| 3 | 22 |
| 4 | 53 |
| 5 | 128 |
| 6 | 309 |
| 7 | 746 |
| 8 | 1801 |
| 9 | 4348 |
| 10 | 10497 |
| 11 | 25342 |
| 12 | 61181 |
| 13 | 147704 |
| 14 | 356589 |
| 15 | 860882 |
| 16 | 2078353 |
| 17 | 5017588 |
| 18 | 12113529 |
| 19 | 29244646 |
| 20 | 70602821 |
| 21 | 170450288 |
| 22 | 411503397 |
| 23 | 993457082 |
| 24 | 2398417561 |
| 25 | 5790292204 |
[1,4,9,22,53,128,309,746,1801,4348,10497,25342, 61181,147704,356589,860882,2078353,5017588, 12113529,29244646,70602821,170450288,411503397, 993457082,2398417561,5790292204] |