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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 67 |
| 5 | 382 |
| 6 | 2327 |
| 7 | 14855 |
| 8 | 98208 |
| 9 | 667180 |
| 10 | 4632647 |
| 11 | 32751382 |
| 12 | 235072482 |
| 13 | 1709232902 |
| 14 | 12568852562 |
| 15 | 93348649555 |
| 16 | 699485096637 |
| 17 | 5283685539096 |
| 18 | 40205412111227 |
| 19 | 308020225286402 |
| 20 | 2374795521493354 |
| 21 | 18419175004781334 |