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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 18 |
| 6 | 53 |
| 7 | 138 |
| 8 | 332 |
| 9 | 757 |
| 10 | 1661 |
| 11 | 3546 |
| 12 | 7424 |
| 13 | 15328 |
| 14 | 31336 |
| 15 | 63618 |
| 16 | 128531 |
| 17 | 258811 |
| 18 | 519956 |
| 19 | 1042992 |
| 20 | 2090009 |
| 21 | 4185231 |
| 22 | 8377158 |
| 23 | 16762853 |
| 24 | 33536516 |
| 25 | 67086633 |
| 26 | 134190278 |
| 27 | 268401718 |
| 28 | 536829625 |
| 29 | 1073691505 |
| 30 | 2147422558 |
[0,0,1,5,18,53,138,332,757,1661,3546,7424,15328, 31336,63618,128531,258811,519956,1042992,2090009, 4185231,8377158,16762853,33536516,67086633, 134190278,268401718,536829625,1073691505, 2147422558] |