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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 88 |
| 5 | 352 |
| 6 | 1471 |
| 7 | 6229 |
| 8 | 26846 |
| 9 | 117199 |
| 10 | 516047 |
| 11 | 2293107 |
| 12 | 10253796 |
| 13 | 46099289 |
| 14 | 208317929 |
| 15 | 945090949 |
| 16 | 4303253468 |
| 17 | 19657172870 |
| 18 | 90040264031 |
| 19 | 413482527121 |
| 20 | 1903072433181 |
| 21 | 8776676137009 |
| 22 | 40552191411904 |
| 23 | 187684377800197 |
| 24 | 869986408121608 |
| 25 | 4038465213131538 |
| 26 | 18771067305712298 |
| 27 | 87355565476467784 |
[1,2,6,23,88,352,1471,6229,26846,117199,516047, 2293107,10253796,46099289,208317929,945090949, 4303253468,19657172870,90040264031,413482527121, 1903072433181,8776676137009,40552191411904, 187684377800197,869986408121608,4038465213131538, 18771067305712298,87355565476467784] |