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 | 4 |
| 2 | 21 |
| 3 | 133 |
| 4 | 977 |
| 5 | 8135 |
| 6 | 75609 |
| 7 | 775667 |
| 8 | 8707057 |
| 9 | 106185715 |
| 10 | 1398451353 |
| 11 | 19786121467 |
| 12 | 299384925569 |
| 13 | 4825081148819 |
| 14 | 82531968286569 |
| 15 | 1493412479919371 |
| 16 | 28504390805515921 |
| 17 | 572363196501249667 |
| 18 | 12061937537478658809 |