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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 40 |
| 5 | 128 |
| 6 | 484 |
| 7 | 1641 |
| 8 | 6334 |
| 9 | 22270 |
| 10 | 86616 |
| 11 | 312454 |
| 12 | 1220466 |
| 13 | 4479292 |
| 14 | 17560954 |
| 15 | 65232393 |
| 16 | 256488726 |
| 17 | 961512650 |
| 18 | 3788566998 |
| 19 | 14305980766 |
| 20 | 56457883232 |
| 21 | 214441375622 |
| 22 | 847362995744 |
| 23 | 3233911640424 |
| 24 | 12792266119044 |
| 25 | 49015447106540 |
| 26 | 194058705431670 |
| 27 | 746071256677748 |
| 28 | 2955972696302066 |
[1,1,4,11,40,128,484,1641,6334,22270,86616,312454, 1220466,4479292,17560954,65232393,256488726, 961512650,3788566998,14305980766,56457883232, 214441375622,847362995744,3233911640424, 12792266119044,49015447106540,194058705431670, 746071256677748,2955972696302066] |