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 | 0 |
| 2 | 4 |
| 3 | 27 |
| 4 | 172 |
| 5 | 1125 |
| 6 | 7591 |
| 7 | 52479 |
| 8 | 369580 |
| 9 | 2640465 |
| 10 | 19082629 |
| 11 | 139207959 |
| 12 | 1023462199 |
| 13 | 7574172879 |
| 14 | 56369211679 |
| 15 | 421563478527 |
| 16 | 3166149812140 |
| 17 | 23868662788809 |
| 18 | 180538738842217 |
| 19 | 1369635435497367 |
| 20 | 10418413517675797 |