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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 44 |
| 5 | 168 |
| 6 | 684 |
| 7 | 2917 |
| 8 | 12434 |
| 9 | 54952 |
| 10 | 244134 |
| 11 | 1100482 |
| 12 | 5016090 |
| 13 | 23007212 |
| 14 | 106468234 |
| 15 | 495348425 |
| 16 | 2317147904 |
| 17 | 10893890888 |
| 18 | 51410034690 |
| 19 | 243569360712 |
| 20 | 1157680823330 |
| 21 | 5518485716846 |
| 22 | 26378212854558 |
| 23 | 126380662190358 |
| 24 | 606859223002138 |
| 25 | 2919830896866662 |
| 26 | 14073944474518660 |
| 27 | 67953617541129074 |
[1,1,4,11,44,168,684,2917,12434,54952,244134, 1100482,5016090,23007212,106468234,495348425, 2317147904,10893890888,51410034690,243569360712, 1157680823330,5518485716846,26378212854558, 126380662190358,606859223002138,2919830896866662, 14073944474518660,67953617541129074] |