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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 30 |
| 2 | 495 |
| 3 | 5890 |
| 4 | 56265 |
| 5 | 456786 |
| 6 | 3263990 |
| 7 | 21017040 |
| 8 | 124018290 |
| 9 | 679118550 |
| 10 | 3484681077 |
| 11 | 16884109080 |
| 12 | 77731521980 |
| 13 | 341784289770 |
| 14 | 1441489548195 |
| 15 | 5852747363518 |
| 16 | 22948550618400 |
| 17 | 87131200662540 |
| 18 | 321100847115950 |
| 19 | 1150962640399770 |
| 20 | 4020058004480100 |
| 21 | 13704611801774340 |
[1,30,495,5890,56265,456786,3263990,21017040, 124018290,679118550,3484681077,16884109080, 77731521980,341784289770,1441489548195, 5852747363518,22948550618400,87131200662540, 321100847115950,1150962640399770,4020058004480100, 13704611801774340] |