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 | 8 |
| 2 | 30 |
| 3 | 110 |
| 4 | 406 |
| 5 | 1512 |
| 6 | 5676 |
| 7 | 21450 |
| 8 | 81510 |
| 9 | 311168 |
| 10 | 1192516 |
| 11 | 4585308 |
| 12 | 17681020 |
| 13 | 68346800 |
| 14 | 264769560 |
| 15 | 1027653570 |
| 16 | 3995416710 |
| 17 | 15557374800 |
| 18 | 60660114900 |
| 19 | 236813267460 |
| 20 | 925540979220 |
| 21 | 3621007518960 |
| 22 | 14179797364200 |
| 23 | 55575657411300 |
| 24 | 217993800897756 |
| 25 | 855702566655552 |