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 | 2 |
| 2 | 9 |
| 3 | 44 |
| 4 | 277 |
| 5 | 1974 |
| 6 | 16213 |
| 7 | 148616 |
| 8 | 1512201 |
| 9 | 16872938 |
| 10 | 205031041 |
| 11 | 2694364452 |
| 12 | 38080715869 |
| 13 | 575998947614 |
| 14 | 9284490424077 |
| 15 | 158882422008704 |
| 16 | 2876883685233553 |
| 17 | 54953707187064786 |
| 18 | 1104409466928407161 |
| 19 | 23295036711306707228 |
| 20 | 514558774836407746341 |