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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 28 |
| 3 | 540 |
| 4 | 9801 |
| 5 | 176176 |
| 6 | 3162160 |
| 7 | 56744793 |
| 8 | 1018249596 |
| 9 | 18271762300 |
| 10 | 327873509425 |
| 11 | 5883451505856 |
| 12 | 105574253853888 |
| 13 | 1894453118539345 |
| 14 | 33994581881622076 |
| 15 | 610008020755286076 |
| 16 | 10946149791725643705 |
| 17 | 196420688230338021808 |
| 18 | 3524626238354441796016 |
| 19 | 63246851602149831726825 |
[0,1,28,540,9801,176176,3162160,56744793, 1018249596,18271762300,327873509425,5883451505856, 105574253853888,1894453118539345, 33994581881622076,610008020755286076, 10946149791725643705,196420688230338021808, 3524626238354441796016,63246851602149831726825] |