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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 11 |
| 4 | 41 |
| 5 | 177 |
| 6 | 820 |
| 7 | 4020 |
| 8 | 20900 |
| 9 | 115473 |
| 10 | 677557 |
| 11 | 4211561 |
| 12 | 27640354 |
| 13 | 190891144 |
| 14 | 1382942176 |
| 15 | 10480109395 |
| 16 | 82864804285 |
| 17 | 682076675105 |
| 18 | 5832741942932 |
| 19 | 51724157711104 |
| 20 | 474869815108196 |
| 21 | 4506715736350193 |
| 22 | 44152005850890065 |
| 23 | 445958869286416705 |
[1,2,4,11,41,177,820,4020,20900,115473,677557, 4211561,27640354,190891144,1382942176,10480109395, 82864804285,682076675105,5832741942932, 51724157711104,474869815108196,4506715736350193, 44152005850890065,445958869286416705] |