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 | 99 |
| 5 | 781 |
| 6 | 7563 |
| 7 | 84253 |
| 8 | 1103595 |
| 9 | 16074589 |
| 10 | 260443083 |
| 11 | 4630046653 |
| 12 | 90017588235 |
| 13 | 1894771249021 |
| 14 | 42957132108075 |
| 15 | 1043136555486493 |
| 16 | 27024421701469995 |
| 17 | 743851294350730141 |
| 18 | 21679544916491784843 |
| 19 | 666932347454809048189 |