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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 21 |
| 3 | 44 |
| 4 | 461 |
| 5 | 966 |
| 6 | 10121 |
| 7 | 21208 |
| 8 | 222201 |
| 9 | 465610 |
| 10 | 4878301 |
| 11 | 10222212 |
| 12 | 107100421 |
| 13 | 224423054 |
| 14 | 2351330961 |
| 15 | 4927084976 |
| 16 | 51622180721 |
| 17 | 108171446418 |
| 18 | 1133336644901 |
| 19 | 2374844736220 |
| 20 | 24881784007101 |
[1,2,21,44,461,966,10121,21208,222201,465610, 4878301,10222212,107100421,224423054,2351330961, 4927084976,51622180721,108171446418,1133336644901, 2374844736220,24881784007101] |