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 | 0 |
| 1 | 0 |
| 2 | 9 |
| 3 | 153 |
| 4 | 1449 |
| 5 | 13617 |
| 6 | 123129 |
| 7 | 1113273 |
| 8 | 10024569 |
| 9 | 90266553 |
| 10 | 812444409 |
| 11 | 7312407993 |
| 12 | 65812080249 |
| 13 | 592312391937 |
| 14 | 5330815197129 |
| 15 | 47977369796313 |
| 16 | 431796361188969 |
| 17 | 3886167547854657 |
| 18 | 34975508227845849 |
| 19 | 314779576724952633 |
| 20 | 2833016193198913689 |
| 21 | 25497145762858874817 |