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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 38 |
| 5 | 291 |
| 6 | 2932 |
| 7 | 36961 |
| 8 | 561948 |
| 9 | 10026505 |
| 10 | 205608536 |
| 11 | 4767440679 |
| 12 | 123373203208 |
| 13 | 3525630110107 |
| 14 | 110284283006640 |
| 15 | 3748357699560961 |
| 16 | 137557910094840848 |
| 17 | 5421179050350334929 |
| 18 | 228359487335194570528 |
| 19 | 10239206473040881277575 |
| 20 | 486909744862576654283616 |
[1,1,2,7,38,291,2932,36961,561948,10026505, 205608536,4767440679,123373203208,3525630110107, 110284283006640,3748357699560961, 137557910094840848,5421179050350334929, 228359487335194570528,10239206473040881277575, 486909744862576654283616] |