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 | 4 |
| 1 | 4 |
| 2 | 9 |
| 3 | 29 |
| 4 | 119 |
| 5 | 599 |
| 6 | 3599 |
| 7 | 25199 |
| 8 | 201599 |
| 9 | 1814399 |
| 10 | 18143999 |
| 11 | 199583999 |
| 12 | 2395007999 |
| 13 | 31135103999 |
| 14 | 435891455999 |
| 15 | 6538371839999 |
| 16 | 104613949439999 |
| 17 | 1778437140479999 |
| 18 | 32011868528639999 |
| 19 | 608225502044159999 |