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| n | a(n) |
|---|---|
| 2 | 0 |
| 3 | 18 |
| 4 | 252 |
| 5 | 1134 |
| 6 | 3312 |
| 7 | 7650 |
| 8 | 15228 |
| 9 | 27342 |
| 10 | 45504 |
| 11 | 71442 |
| 12 | 107100 |
| 13 | 154638 |
| 14 | 216432 |
| 15 | 295074 |
| 16 | 393372 |
| 17 | 514350 |
| 18 | 661248 |
| 19 | 837522 |
| 20 | 1046844 |
| 21 | 1293102 |
| 22 | 1580400 |
| 23 | 1913058 |
| 24 | 2295612 |
| 25 | 2732814 |
| 26 | 3229632 |
| 27 | 3791250 |
| 28 | 4423068 |
| 29 | 5130702 |
| 30 | 5919984 |
[0,18,252,1134,3312,7650,15228,27342,45504,71442, 107100,154638,216432,295074,393372,514350,661248, 837522,1046844,1293102,1580400,1913058,2295612, 2732814,3229632,3791250,4423068,5130702,5919984] |