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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 69 |
| 4 | 936 |
| 5 | 16290 |
| 6 | 345857 |
| 7 | 8666413 |
| 8 | 250355800 |
| 9 | 8191830942 |
| 10 | 299452606190 |
| 11 | 12095028921250 |
| 12 | 534924268768540 |
| 13 | 25710497506696860 |
| 14 | 1334410348734174285 |
| 15 | 74379234152676275325 |
| 16 | 4431350132232658244400 |
| 17 | 281020603194039519937590 |
| 18 | 18900157831016574533520330 |
| 19 | 1343698678390575915132318870 |
[1,1,7,69,936,16290,345857,8666413,250355800, 8191830942,299452606190,12095028921250, 534924268768540,25710497506696860, 1334410348734174285,74379234152676275325, 4431350132232658244400,281020603194039519937590, 18900157831016574533520330, 1343698678390575915132318870] |