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 | 10 |
| 4 | 21 |
| 5 | 483 |
| 6 | 1485 |
| 7 | 56628 |
| 8 | 225225 |
| 9 | 12317877 |
| 10 | 59520825 |
| 11 | 4304016990 |
| 12 | 24325703325 |
| 13 | 2208143028375 |
| 14 | 14230536445125 |
| 15 | 1564439686929000 |
| 16 | 11288163762500625 |
| 17 | 1463987089109939625 |
| 18 | 11665426077721040625 |
| 19 | 1749439028845202483250 |
| 20 | 15230046989184655753125 |