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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 25 |
| 5 | 61 |
| 6 | 1201 |
| 7 | 7771 |
| 8 | 30577 |
| 9 | 514585 |
| 10 | 8089921 |
| 11 | 63701551 |
| 12 | 832599241 |
| 13 | 14055894997 |
| 14 | 137066892145 |
| 15 | 3084240161731 |
| 16 | 70859008063201 |
| 17 | 849408115312561 |
| 18 | 15997591979202817 |
| 19 | 358582896987674455 |
| 20 | 6017079190150763641 |
| 21 | 209473179919282488301 |
[1,1,1,7,25,61,1201,7771,30577,514585,8089921, 63701551,832599241,14055894997,137066892145, 3084240161731,70859008063201,849408115312561, 15997591979202817,358582896987674455, 6017079190150763641,209473179919282488301] |