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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 33 |
| 3 | 185 |
| 4 | 1065 |
| 5 | 6276 |
| 6 | 37711 |
| 7 | 230277 |
| 8 | 1425180 |
| 9 | 8920915 |
| 10 | 56382321 |
| 11 | 359325561 |
| 12 | 2306603557 |
| 13 | 14900834070 |
| 14 | 96801107625 |
| 15 | 631995206707 |
| 16 | 4144614844047 |
| 17 | 27289670546697 |
| 18 | 180339237891360 |
| 19 | 1195684324845420 |
| 20 | 7951560286540908 |
| 21 | 53025939926690233 |
| 22 | 354509890878236583 |
[1,6,33,185,1065,6276,37711,230277,1425180, 8920915,56382321,359325561,2306603557,14900834070, 96801107625,631995206707,4144614844047, 27289670546697,180339237891360,1195684324845420, 7951560286540908,53025939926690233, 354509890878236583] |