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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 48 |
| 5 | 166 |
| 6 | 597 |
| 7 | 2215 |
| 8 | 8510 |
| 9 | 33266 |
| 10 | 132505 |
| 11 | 537363 |
| 12 | 2202785 |
| 13 | 9140543 |
| 14 | 38334918 |
| 15 | 162006061 |
| 16 | 690358870 |
| 17 | 2962720562 |
| 18 | 12787564112 |
| 19 | 55521222256 |
| 20 | 242295294818 |
| 21 | 1062048148918 |
| 22 | 4675861534171 |
| 23 | 20666381911613 |
| 24 | 91659316769501 |
| 25 | 407917282709291 |
| 26 | 1820948836147556 |
| 27 | 8151519838832373 |
[1,2,5,15,48,166,597,2215,8510,33266,132505, 537363,2202785,9140543,38334918,162006061, 690358870,2962720562,12787564112,55521222256, 242295294818,1062048148918,4675861534171, 20666381911613,91659316769501,407917282709291, 1820948836147556,8151519838832373] |