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 | 0 |
| 3 | 25 |
| 4 | 1847 |
| 5 | 162531 |
| 6 | 2501726 |
| 7 | 21243084 |
| 8 | 119138166 |
| 9 | 502726650 |
| 10 | 1724809105 |
| 11 | 5059647669 |
| 12 | 13132889249 |
| 13 | 30905051345 |
| 14 | 67124176002 |
| 15 | 136380034610 |
| 16 | 261909043488 |
| 17 | 479315827404 |
| 18 | 841394145399 |
| 19 | 1424246670499 |
| 20 | 2334919892115 |