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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 24 |
| 6 | 81 |
| 7 | 250 |
| 8 | 732 |
| 9 | 2073 |
| 10 | 5742 |
| 11 | 15664 |
| 12 | 42273 |
| 13 | 113202 |
| 14 | 301428 |
| 15 | 799273 |
| 16 | 2112774 |
| 17 | 5571816 |
| 18 | 14668209 |
| 19 | 38563882 |
| 20 | 101285580 |
| 21 | 265817145 |
| 22 | 697214430 |
| 23 | 1827923296 |
| 24 | 4790749761 |
| 25 | 12552714594 |
| 26 | 32884171236 |
| 27 | 86133353545 |
| 28 | 225582998262 |
| 29 | 590749858968 |
| 30 | 1546935014097 |