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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 51 |
| 4 | 228 |
| 5 | 1049 |
| 6 | 4912 |
| 7 | 23310 |
| 8 | 111611 |
| 9 | 538350 |
| 10 | 2611000 |
| 11 | 12719428 |
| 12 | 62181672 |
| 13 | 304871715 |
| 14 | 1498393712 |
| 15 | 7379275195 |
| 16 | 36403845579 |
| 17 | 179852166090 |
| 18 | 889676649510 |
| 19 | 4405782364400 |
| 20 | 21838700181353 |
| 21 | 108340738964579 |
| 22 | 537866816660190 |
| 23 | 2672014854526180 |
| 24 | 13281659061969012 |
| 25 | 66052268381557539 |
| 26 | 328640757399863619 |
[1,3,12,51,228,1049,4912,23310,111611,538350, 2611000,12719428,62181672,304871715,1498393712, 7379275195,36403845579,179852166090,889676649510, 4405782364400,21838700181353,108340738964579, 537866816660190,2672014854526180, 13281659061969012,66052268381557539, 328640757399863619] |