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 | 28 |
| 3 | 140 |
| 4 | 620 |
| 5 | 2604 |
| 6 | 10668 |
| 7 | 43180 |
| 8 | 173740 |
| 9 | 697004 |
| 10 | 2792108 |
| 11 | 11176620 |
| 12 | 44722860 |
| 13 | 178924204 |
| 14 | 715762348 |
| 15 | 2863180460 |