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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 22 |
| 2 | 220 |
| 3 | 1320 |
| 4 | 5302 |
| 5 | 15224 |
| 6 | 33528 |
| 7 | 63360 |
| 8 | 116380 |
| 9 | 209550 |
| 10 | 339064 |
| 11 | 491768 |
| 12 | 719400 |
| 13 | 1095160 |
| 14 | 1538416 |
| 15 | 1964160 |
| 16 | 2624182 |
| 17 | 3696880 |
| 18 | 4763220 |
| 19 | 5686648 |
| 20 | 7217144 |
| 21 | 9528816 |
| 22 | 11676280 |
| 23 | 13495680 |
| 24 | 16317048 |
| 25 | 20787470 |
| 26 | 25022184 |
| 27 | 27785120 |
| 28 | 32503680 |
[1,22,220,1320,5302,15224,33528,63360,116380, 209550,339064,491768,719400,1095160,1538416, 1964160,2624182,3696880,4763220,5686648,7217144, 9528816,11676280,13495680,16317048,20787470, 25022184,27785120,32503680] |