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 | 4 |
| 1 | 15 |
| 2 | 52 |
| 3 | 210 |
| 4 | 1007 |
| 5 | 5156 |
| 6 | 25571 |
| 7 | 133293 |
| 8 | 727082 |
| 9 | 3874464 |
| 10 | 21072166 |
| 11 | 117829671 |
| 12 | 654556778 |