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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 25 |
| 4 | 141 |
| 5 | 911 |
| 6 | 6703 |
| 7 | 55581 |
| 8 | 513929 |
| 9 | 5248891 |
| 10 | 58724211 |
| 11 | 714554633 |
| 12 | 9397715341 |
| 13 | 132870076119 |
| 14 | 2009977939271 |
| 15 | 32396622193141 |
| 16 | 554297204755473 |
| 17 | 10034223725151731 |
| 18 | 191617109450287579 |
| 19 | 3849745645109036001 |