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 | 9 |
| 2 | 57 |
| 3 | 369 |
| 4 | 2481 |
| 5 | 17049 |
| 6 | 118377 |
| 7 | 825729 |
| 8 | 5771361 |
| 9 | 40373289 |
| 10 | 282534297 |
| 11 | 1977503889 |
| 12 | 13841818641 |
| 13 | 96890604729 |
| 14 | 678227855817 |
| 15 | 4747575858849 |
| 16 | 33232973616321 |
| 17 | 232630643127369 |
| 18 | 1628413985330937 |
| 19 | 11398896347634609 |