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 | 0 |
| 2 | 2 |
| 3 | 15 |
| 4 | 82 |
| 5 | 405 |
| 6 | 1891 |
| 7 | 8554 |
| 8 | 37850 |
| 9 | 164985 |
| 10 | 710893 |
| 11 | 3036726 |
| 12 | 12880847 |
| 13 | 54331550 |
| 14 | 228089538 |
| 15 | 953811972 |
| 16 | 3975120810 |
| 17 | 16519242465 |
| 18 | 68474376025 |
| 19 | 283211458750 |
| 20 | 1169062910873 |
| 21 | 4817380232522 |
| 22 | 19819870885230 |
| 23 | 81429323786460 |
| 24 | 334120527783367 |
| 25 | 1369374666890230 |