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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 15 |
| 7 | 75 |
| 8 | 310 |
| 9 | 1060 |
| 10 | 3281 |
| 11 | 9564 |
| 12 | 26719 |
| 13 | 72239 |
| 14 | 191569 |
| 15 | 500797 |
| 16 | 1299925 |
| 17 | 3362473 |
| 18 | 8697198 |
| 19 | 22513878 |
| 20 | 58352126 |
| 21 | 151267141 |
| 22 | 391728632 |
| 23 | 1011734975 |
| 24 | 2602330120 |
| 25 | 6657204192 |
| 26 | 16920629023 |
| 27 | 42697311397 |
| 28 | 106912113623 |
| 29 | 265560809521 |
| 30 | 654270114555 |
[0,0,0,0,0,15,75,310,1060,3281,9564,26719,72239, 191569,500797,1299925,3362473,8697198,22513878, 58352126,151267141,391728632,1011734975, 2602330120,6657204192,16920629023,42697311397, 106912113623,265560809521,654270114555] |