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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 6 |
| 6 | 13 |
| 7 | 25 |
| 8 | 45 |
| 9 | 91 |
| 10 | 154 |
| 11 | 322 |
| 12 | 525 |
| 13 | 1125 |
| 14 | 1793 |
| 15 | 3921 |
| 16 | 6153 |
| 17 | 13671 |
| 18 | 21206 |
| 19 | 47718 |
| 20 | 73359 |
| 21 | 166800 |
| 22 | 254607 |
| 23 | 583947 |
| 24 | 886171 |
| 25 | 2047375 |
| 26 | 3091971 |
| 27 | 7188451 |
| 28 | 10811671 |
| 29 | 25272481 |
| 30 | 37877401 |
| 31 | 88959929 |
| 32 | 132924649 |
| 33 | 313498639 |
[0,0,0,3,6,13,25,45,91,154,322,525,1125,1793,3921, 6153,13671,21206,47718,73359,166800,254607,583947, 886171,2047375,3091971,7188451,10811671,25272481, 37877401,88959929,132924649,313498639] |