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 | 13 |
| 2 | 97 |
| 3 | 613 |
| 4 | 4457 |
| 5 | 33063 |
| 6 | 250669 |
| 7 | 1923655 |
| 8 | 14884769 |
| 9 | 115789951 |
| 10 | 903866897 |
| 11 | 7071440807 |
| 12 | 55403165585 |
| 13 | 434470766327 |
| 14 | 3409117220977 |
| 15 | 26760021485703 |
| 16 | 210104387835521 |
| 17 | 1649871912782039 |
| 18 | 12957097087570897 |
| 19 | 101763543017243975 |