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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 28 |
| 5 | 127 |
| 6 | 650 |
| 7 | 3737 |
| 8 | 23996 |
| 9 | 170866 |
| 10 | 1338578 |
| 11 | 11446714 |
| 12 | 106063630 |
| 13 | 1057817614 |
| 14 | 11288886056 |
| 15 | 128243813228 |
| 16 | 1543828592478 |
| 17 | 19616461337281 |
| 18 | 262178561430244 |
| 19 | 3674568043513202 |
| 20 | 53861542554953612 |
| 21 | 823710227331537712 |
[1,2,7,28,127,650,3737,23996,170866,1338578, 11446714,106063630,1057817614,11288886056, 128243813228,1543828592478,19616461337281, 262178561430244,3674568043513202, 53861542554953612,823710227331537712] |