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 | 3 |
| 2 | 19 |
| 3 | 85 |
| 4 | 355 |
| 5 | 1435 |
| 6 | 5717 |
| 7 | 22645 |
| 8 | 89521 |
| 9 | 353735 |
| 10 | 1397863 |
| 11 | 5525341 |
| 12 | 21846421 |
| 13 | 86403027 |
| 14 | 341822335 |
| 15 | 1352660761 |
| 16 | 5354124895 |
| 17 | 21197945407 |
| 18 | 83945924393 |
| 19 | 332507403625 |
| 20 | 1317329758675 |
| 21 | 5220055148883 |
| 22 | 20688989887169 |
| 23 | 82013159349085 |
| 24 | 325165555406795 |
| 25 | 1289434099001055 |
| 26 | 5114044079094817 |
| 27 | 20286061330030705 |
| 28 | 80481556028898031 |