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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 58 |
| 5 | 223 |
| 6 | 858 |
| 7 | 3301 |
| 8 | 12700 |
| 9 | 48861 |
| 10 | 187984 |
| 11 | 723235 |
| 12 | 2782518 |
| 13 | 10705243 |
| 14 | 41186518 |
| 15 | 158457801 |
| 16 | 609638200 |
| 17 | 2345474521 |
| 18 | 9023795964 |
| 19 | 34717449655 |
| 20 | 133569211378 |
| 21 | 513883779063 |
| 22 | 1977076420978 |
| 23 | 7606449811501 |
| 24 | 29264462476500 |
| 25 | 112589813284981 |
| 26 | 433169277095944 |
[0,1,4,15,58,223,858,3301,12700,48861,187984, 723235,2782518,10705243,41186518,158457801, 609638200,2345474521,9023795964,34717449655, 133569211378,513883779063,1977076420978, 7606449811501,29264462476500,112589813284981, 433169277095944] |