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 | 2 |
| 2 | 6 |
| 3 | 25 |
| 4 | 129 |
| 5 | 771 |
| 6 | 5172 |
| 7 | 38280 |
| 8 | 308987 |
| 9 | 2695586 |
| 10 | 25231269 |
| 11 | 251869681 |
| 12 | 2667876382 |
| 13 | 29856632341 |
| 14 | 351717286357 |
| 15 | 4347357161694 |
| 16 | 56222019376378 |
| 17 | 758836553993985 |
| 18 | 10665452531786380 |
| 19 | 155785594704483911 |