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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 10 |
| 3 | 24 |
| 4 | 54 |
| 5 | 120 |
| 6 | 260 |
| 7 | 560 |
| 8 | 1190 |
| 9 | 2520 |
| 10 | 5292 |
| 11 | 11088 |
| 12 | 23100 |
| 13 | 48048 |
| 14 | 99528 |
| 15 | 205920 |
| 16 | 424710 |
| 17 | 875160 |
| 18 | 1798940 |
| 19 | 3695120 |
| 20 | 7574996 |
| 21 | 15519504 |
| 22 | 31744440 |
| 23 | 64899744 |
| 24 | 132503644 |
| 25 | 270415600 |
| 26 | 551231800 |
| 27 | 1123264800 |
| 28 | 2286646200 |
| 29 | 4653525600 |
[1,4,10,24,54,120,260,560,1190,2520,5292,11088, 23100,48048,99528,205920,424710,875160,1798940, 3695120,7574996,15519504,31744440,64899744, 132503644,270415600,551231800,1123264800, 2286646200,4653525600] |