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 | 1 |
| 3 | 4 |
| 4 | 23 |
| 5 | 241 |
| 6 | 3732 |
| 7 | 83987 |
| 8 | 2666729 |
| 9 | 117807298 |
| 10 | 7217946453 |
| 11 | 612089089261 |
| 12 | 71991021616582 |
| 13 | 11761139981560581 |
| 14 | 2675674695560997301 |
| 15 | 849270038176762472316 |
| 16 | 376910699272413914514283 |
| 17 | 234289022942841270608166061 |
| 18 | 204344856617470777364053906796 |