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 | 2 |
| 2 | 21 |
| 3 | 244 |
| 4 | 3055 |
| 5 | 40116 |
| 6 | 544103 |
| 7 | 7553960 |
| 8 | 106734195 |
| 9 | 1528937200 |
| 10 | 22143771386 |
| 11 | 323613807672 |
| 12 | 4765050473521 |
| 13 | 70611124679564 |
| 14 | 1052084386116915 |
| 15 | 15750153504353872 |
| 16 | 236766112174722235 |
| 17 | 3572264808332407512 |
| 18 | 54073065371555283968 |
| 19 | 820886646834780680640 |