This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 17 |
| 2 | 289 |
| 3 | 4913 |
| 4 | 83521 |
| 5 | 1419857 |
| 6 | 24137569 |
| 7 | 410338673 |
| 8 | 6975757441 |
| 9 | 118587876497 |
| 10 | 2015993900449 |
| 11 | 34271896307633 |
| 12 | 582622237229761 |
| 13 | 9904578032905937 |
| 14 | 168377826559400929 |
| 15 | 2862423051509815793 |
| 16 | 48661191875666868481 |
| 17 | 827240261886336764177 |
| 18 | 14063084452067724991009 |
| 19 | 239072435685151324847153 |
| 20 | 4064231406647572522401601 |