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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 137 |
| 4 | 1572 |
| 5 | 22457 |
| 6 | 384934 |
| 7 | 7699449 |
| 8 | 176004376 |
| 9 | 4526214641 |
| 10 | 129331581954 |
| 11 | 4065059876033 |
| 12 | 139385578253524 |
| 13 | 5177627842411065 |
| 14 | 207123084913936174 |
| 15 | 8877473910719477033 |
| 16 | 405862594146337680816 |
| 17 | 19715036609777115714401 |
| 18 | 1014004150296746677804666 |
[1,3,16,137,1572,22457,384934,7699449,176004376, 4526214641,129331581954,4065059876033, 139385578253524,5177627842411065, 207123084913936174,8877473910719477033, 405862594146337680816,19715036609777115714401, 1014004150296746677804666] |