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 | 2 |
| 3 | 7 |
| 4 | 34 |
| 5 | 203 |
| 6 | 1398 |
| 7 | 10706 |
| 8 | 89120 |
| 9 | 794347 |
| 10 | 7502170 |
| 11 | 74511150 |
| 12 | 773864654 |
| 13 | 8368430208 |
| 14 | 93905460014 |
| 15 | 1090519614152 |
| 16 | 13077315637592 |
| 17 | 161643281777801 |
| 18 | 2056306418177832 |
| 19 | 26887064722265250 |
| 20 | 360939404438509866 |