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 | 3 |
| 3 | 13 |
| 4 | 74 |
| 5 | 531 |
| 6 | 4563 |
| 7 | 45753 |
| 8 | 524345 |
| 9 | 6760039 |
| 10 | 96837333 |
| 11 | 1525909903 |
| 12 | 26230304235 |
| 13 | 488472319271 |
| 14 | 9796281435125 |
| 15 | 210496933103743 |
| 16 | 4824574494068495 |
| 17 | 117490079786298641 |
| 18 | 3029472152485535343 |
| 19 | 82454398253005541089 |
| 20 | 2362311059301928969755 |
| 21 | 71063998308414194250901 |