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 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 57 |
| 5 | 223 |
| 6 | 948 |
| 7 | 3940 |
| 8 | 16994 |
| 9 | 72964 |
| 10 | 317959 |
| 11 | 1385592 |
| 12 | 6085763 |
| 13 | 26738139 |
| 14 | 117939291 |
| 15 | 520553999 |
| 16 | 2301781692 |
| 17 | 10181786176 |
| 18 | 45074744448 |
| 19 | 199558036891 |
| 20 | 883670342156 |
| 21 | 3912320450786 |