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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 33 |
| 5 | 265 |
| 6 | 2657 |
| 7 | 31949 |
| 8 | 447809 |
| 9 | 7170193 |
| 10 | 129126849 |
| 11 | 2583427349 |
| 12 | 56849678689 |
| 13 | 1364649651865 |
| 14 | 35486043526177 |
| 15 | 993722660727005 |
| 16 | 29814403968536193 |
| 17 | 954131785638216481 |
| 18 | 32442465432874088321 |
| 19 | 1167988313532759193637 |
| 20 | 44385462193094951063201 |
[1,1,1,5,33,265,2657,31949,447809,7170193, 129126849,2583427349,56849678689,1364649651865, 35486043526177,993722660727005,29814403968536193, 954131785638216481,32442465432874088321, 1167988313532759193637,44385462193094951063201] |