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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 13 |
| 4 | 46 |
| 5 | 160 |
| 6 | 571 |
| 7 | 2095 |
| 8 | 7802 |
| 9 | 29326 |
| 10 | 111040 |
| 11 | 422862 |
| 12 | 1617611 |
| 13 | 6210935 |
| 14 | 23922207 |
| 15 | 92387315 |
| 16 | 357629430 |
| 17 | 1387192894 |
| 18 | 5390374430 |
| 19 | 20979391112 |
| 20 | 81768490420 |
| 21 | 319107181678 |
| 22 | 1246785919174 |
| 23 | 4876478734046 |
| 24 | 19091509694075 |
[2,4,13,46,160,571,2095,7802,29326,111040,422862, 1617611,6210935,23922207,92387315,357629430, 1387192894,5390374430,20979391112,81768490420, 319107181678,1246785919174,4876478734046, 19091509694075] |