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 | 5 |
| 3 | 30 |
| 4 | 224 |
| 5 | 1871 |
| 6 | 16771 |
| 7 | 157668 |
| 8 | 1533970 |
| 9 | 15314626 |
| 10 | 156008660 |
| 11 | 1615147014 |
| 12 | 16944659846 |
| 13 | 179746651907 |
| 14 | 1924700759635 |
| 15 | 20776060271760 |
| 16 | 225838715259574 |
| 17 | 2469974866825150 |
| 18 | 27160344857205806 |
| 19 | 300101157823582668 |