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 | 4 |
| 2 | 32 |
| 3 | 228 |
| 4 | 1655 |
| 5 | 11978 |
| 6 | 86731 |
| 7 | 627960 |
| 8 | 4546684 |
| 9 | 32919766 |
| 10 | 238352021 |
| 11 | 1725762060 |
| 12 | 12495193865 |
| 13 | 90470101964 |
| 14 | 655039004548 |
| 15 | 4742739182904 |
| 16 | 34339290944491 |
| 17 | 248629928211118 |
| 18 | 1800178148762579 |
| 19 | 13033995507292632 |
| 20 | 94371237091674512 |
| 21 | 683284752187469642 |