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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 15 |
| 4 | 264 |
| 5 | 1700 |
| 6 | 6900 |
| 7 | 21315 |
| 8 | 54880 |
| 9 | 123984 |
| 10 | 253800 |
| 11 | 480975 |
| 12 | 856680 |
| 13 | 1450020 |
| 14 | 2351804 |
| 15 | 3678675 |
| 16 | 5577600 |
| 17 | 8230720 |
| 18 | 11860560 |
| 19 | 16735599 |
| 20 | 23176200 |
| 21 | 31560900 |
| 22 | 42333060 |
| 23 | 56007875 |
| 24 | 73179744 |
| 25 | 94530000 |
| 26 | 120835000 |
| 27 | 152974575 |
| 28 | 191940840 |
| 29 | 238847364 |
| 30 | 294938700 |
[0,0,15,264,1700,6900,21315,54880,123984,253800, 480975,856680,1450020,2351804,3678675,5577600, 8230720,11860560,16735599,23176200,31560900, 42333060,56007875,73179744,94530000,120835000, 152974575,191940840,238847364,294938700] |