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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 27 |
| 4 | 108 |
| 5 | 440 |
| 6 | 1812 |
| 7 | 7514 |
| 8 | 31307 |
| 9 | 130883 |
| 10 | 548547 |
| 11 | 2303413 |
| 12 | 9686617 |
| 13 | 40783083 |
| 14 | 171868037 |
| 15 | 724837891 |
| 16 | 3058850316 |
| 17 | 12915186640 |
| 18 | 54554594416 |
| 19 | 230526280814 |
| 20 | 974414815782 |
| 21 | 4119854160332 |
| 22 | 17422801069670 |
| 23 | 73695109608352 |
| 24 | 311768697325788 |
| 25 | 1319136935150530 |
[1,2,7,27,108,440,1812,7514,31307,130883,548547, 2303413,9686617,40783083,171868037,724837891, 3058850316,12915186640,54554594416,230526280814, 974414815782,4119854160332,17422801069670, 73695109608352,311768697325788,1319136935150530] |