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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 49 |
| 5 | 184 |
| 6 | 772 |
| 7 | 3233 |
| 8 | 14051 |
| 9 | 61341 |
| 10 | 273080 |
| 11 | 1225875 |
| 12 | 5565975 |
| 13 | 25405343 |
| 14 | 116867558 |
| 15 | 540770706 |
| 16 | 2513900350 |
| 17 | 11735911545 |
| 18 | 55025784823 |
| 19 | 258855070126 |
| 20 | 1221450625311 |
| 21 | 5780287183370 |
| 22 | 27425894994969 |
| 23 | 130429123332310 |
| 24 | 621587004920357 |
| 25 | 2968242924596417 |
| 26 | 14200288504162876 |
| 27 | 68045686162460783 |
[1,1,4,12,49,184,772,3233,14051,61341,273080, 1225875,5565975,25405343,116867558,540770706, 2513900350,11735911545,55025784823,258855070126, 1221450625311,5780287183370,27425894994969, 130429123332310,621587004920357,2968242924596417, 14200288504162876,68045686162460783] |