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 | 1 |
| 2 | 6 |
| 3 | 43 |
| 4 | 352 |
| 5 | 3114 |
| 6 | 29004 |
| 7 | 280221 |
| 8 | 2782476 |
| 9 | 28221784 |
| 10 | 291138856 |
| 11 | 3045298326 |
| 12 | 32222872906 |
| 13 | 344293297768 |
| 14 | 3709496350512 |
| 15 | 40256666304723 |
| 16 | 439645950112788 |
| 17 | 4828214610825948 |
| 18 | 53286643424088024 |
| 19 | 590705976259292856 |
| 20 | 6574347641664629388 |
| 21 | 73433973722458186608 |