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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 36 |
| 5 | 88 |
| 6 | 516 |
| 7 | 2076 |
| 8 | 7372 |
| 9 | 27108 |
| 10 | 92436 |
| 11 | 308980 |
| 12 | 1013112 |
| 13 | 3250572 |
| 14 | 10288376 |
| 15 | 32139960 |
| 16 | 99287748 |
| 17 | 303857760 |
| 18 | 922134588 |
| 19 | 2777950524 |
| 20 | 8314125460 |
| 21 | 24737931132 |
| 22 | 73218906420 |
| 23 | 215681560092 |
| 24 | 632587894224 |
| 25 | 1848037669164 |
| 26 | 5379301732896 |
[0,0,0,36,88,516,2076,7372,27108,92436,308980, 1013112,3250572,10288376,32139960,99287748, 303857760,922134588,2777950524,8314125460, 24737931132,73218906420,215681560092,632587894224, 1848037669164,5379301732896] |