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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 122 |
| 5 | 534 |
| 6 | 2444 |
| 7 | 11220 |
| 8 | 52536 |
| 9 | 246840 |
| 10 | 1172104 |
| 11 | 5580649 |
| 12 | 26741260 |
| 13 | 128421666 |
| 14 | 619275234 |
| 15 | 2991804319 |
| 16 | 14494707351 |
| 17 | 70332745402 |
| 18 | 341974970533 |
| 19 | 1664926463193 |
| 20 | 8118358471204 |
| 21 | 39629464167851 |
| 22 | 193684934880890 |
| 23 | 947500660895119 |
| 24 | 4639699212194171 |
| 25 | 22737806937630413 |
| 26 | 111522036284003882 |
[1,2,7,28,122,534,2444,11220,52536,246840,1172104, 5580649,26741260,128421666,619275234,2991804319, 14494707351,70332745402,341974970533, 1664926463193,8118358471204,39629464167851, 193684934880890,947500660895119,4639699212194171, 22737806937630413,111522036284003882] |