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) |
|---|---|
| 3 | 1 |
| 4 | 1 |
| 5 | 7 |
| 6 | 73 |
| 7 | 879 |
| 8 | 11713 |
| 9 | 167423 |
| 10 | 2519937 |
| 11 | 39458047 |
| 12 | 637446145 |
| 13 | 10561615871 |
| 14 | 178683815937 |
| 15 | 3076487458815 |
| 16 | 53766284722177 |
| 17 | 951817354412031 |
| 18 | 17039752595865601 |
| 19 | 308068940431556607 |
| 20 | 5618467344224354305 |