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A357703 as a simple table
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 9 |
| 4 | 42 |
| 5 | 240 |
| 6 | 1614 |
| 7 | 12474 |
| 8 | 108900 |
| 9 | 1059696 |
| 10 | 11371932 |
| 11 | 133410420 |
| 12 | 1698541416 |
| 13 | 23324023008 |
| 14 | 343606235544 |
| 15 | 5405580540360 |
| 16 | 90445832210448 |
| 17 | 1603781918563968 |
| 18 | 30042007763367600 |
| 19 | 592788643008571152 |
| 20 | 12289695299276133024 |
| 21 | 267079782474700715520 |
[1,0,3,9,42,240,1614,12474,108900,1059696, 11371932,133410420,1698541416,23324023008, 343606235544,5405580540360,90445832210448, 1603781918563968,30042007763367600, 592788643008571152,12289695299276133024, 267079782474700715520] |