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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 26 |
| 5 | 184 |
| 6 | 1338 |
| 7 | 11652 |
| 8 | 108210 |
| 9 | 1140336 |
| 10 | 12849714 |
| 11 | 159858900 |
| 12 | 2117522754 |
| 13 | 30442090248 |
| 14 | 463511103426 |
| 15 | 7569181895436 |
| 16 | 130254363597330 |
| 17 | 2383020441932256 |
| 18 | 45738553437874962 |
| 19 | 927010880040945924 |
[0,1,5,26,184,1338,11652,108210,1140336,12849714, 159858900,2117522754,30442090248,463511103426, 7569181895436,130254363597330,2383020441932256, 45738553437874962,927010880040945924] |