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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 27 |
| 6 | 167 |
| 7 | 1451 |
| 8 | 12672 |
| 9 | 133356 |
| 10 | 1573608 |
| 11 | 20731512 |
| 12 | 299642958 |
| 13 | 4732486932 |
| 14 | 81201040470 |
| 15 | 1500094187292 |
| 16 | 29730606352920 |
| 17 | 628968809015766 |
| 18 | 14147458062941100 |
| 19 | 337143091156288002 |
| 20 | 8485143902146640124 |