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 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 17 |
| 6 | 131 |
| 7 | 915 |
| 8 | 6553 |
| 9 | 47026 |
| 10 | 341888 |
| 11 | 2505449 |
| 12 | 18534827 |
| 13 | 138224058 |
| 14 | 1038594326 |
| 15 | 7856087894 |
| 16 | 59782042225 |
| 17 | 457359506070 |
| 18 | 3515816578512 |
| 19 | 27143401299351 |
| 20 | 210372490707568 |