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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 23 |
| 4 | 96 |
| 5 | 354 |
| 6 | 1534 |
| 7 | 6066 |
| 8 | 27086 |
| 9 | 110747 |
| 10 | 501581 |
| 11 | 2106197 |
| 12 | 9652273 |
| 13 | 41197318 |
| 14 | 190177775 |
| 15 | 823152541 |
| 16 | 3823689704 |
| 17 | 16712997276 |
| 18 | 77975705509 |
| 19 | 343795036066 |
| 20 | 1610189417951 |
| 21 | 7146230164544 |
| 22 | 33567668815079 |
| 23 | 149865434397075 |
| 24 | 705794290614539 |
| 25 | 3166119611677456 |
| 26 | 14941943012113508 |
| 27 | 67320026715907005 |
[1,2,7,23,96,354,1534,6066,27086,110747,501581, 2106197,9652273,41197318,190177775,823152541, 3823689704,16712997276,77975705509,343795036066, 1610189417951,7146230164544,33567668815079, 149865434397075,705794290614539,3166119611677456, 14941943012113508,67320026715907005] |