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 | -6 |
| 2 | 6 |
| 3 | 4 |
| 4 | 6 |
| 5 | 12 |
| 6 | 28 |
| 7 | 72 |
| 8 | 198 |
| 9 | 572 |
| 10 | 1716 |
| 11 | 5304 |
| 12 | 16796 |
| 13 | 54264 |
| 14 | 178296 |
| 15 | 594320 |
| 16 | 2005830 |
| 17 | 6843420 |
| 18 | 23571780 |
| 19 | 81880920 |
| 20 | 286583220 |
| 21 | 1009864680 |
| 22 | 3580429320 |
| 23 | 12765008880 |
| 24 | 45741281820 |
| 25 | 164668614552 |
| 26 | 595340375688 |
| 27 | 2160865067312 |
| 28 | 7871722745208 |
| 29 | 28772503827312 |