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 | 4 |
| 3 | 19 |
| 4 | 107 |
| 5 | 647 |
| 6 | 4167 |
| 7 | 27847 |
| 8 | 191747 |
| 9 | 1349743 |
| 10 | 9671316 |
| 11 | 70297105 |
| 12 | 517079157 |
| 13 | 3841701488 |
| 14 | 28787546360 |
| 15 | 217317367487 |
| 16 | 1651144126659 |
| 17 | 12616570941114 |
| 18 | 96891439504019 |
| 19 | 747452640586114 |
| 20 | 5789461514134881 |