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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 26 |
| 4 | 147 |
| 5 | 892 |
| 6 | 5876 |
| 7 | 40490 |
| 8 | 290020 |
| 9 | 2136488 |
| 10 | 16113254 |
| 11 | 123878966 |
| 12 | 968017330 |
| 13 | 7670113856 |
| 14 | 61510346760 |
| 15 | 498496979754 |
| 16 | 4077605379276 |
| 17 | 33629943832280 |
| 18 | 279413323740280 |
| 19 | 2336935584712872 |
| 20 | 19663001667901339 |
| 21 | 166348460274745684 |
| 22 | 1414318445894183076 |
| 23 | 12079654921382780966 |
[1,2,6,26,147,892,5876,40490,290020,2136488, 16113254,123878966,968017330,7670113856, 61510346760,498496979754,4077605379276, 33629943832280,279413323740280,2336935584712872, 19663001667901339,166348460274745684, 1414318445894183076,12079654921382780966] |