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 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 230 |
| 5 | 2565 |
| 6 | 34516 |
| 7 | 544423 |
| 8 | 9857583 |
| 9 | 201664780 |
| 10 | 4603336725 |
| 11 | 116059191472 |
| 12 | 3204682702923 |
| 13 | 96226940232235 |
| 14 | 3122975927539860 |
| 15 | 108970956192622980 |
| 16 | 4069312064491308140 |
| 17 | 161969813446983961395 |
| 18 | 6846708764857861662741 |
| 19 | 306381118887919045527510 |