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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 7 |
| 5 | 28 |
| 6 | 85 |
| 7 | 224 |
| 8 | 567 |
| 9 | 1485 |
| 10 | 4117 |
| 11 | 11802 |
| 12 | 33909 |
| 13 | 96182 |
| 14 | 269402 |
| 15 | 750275 |
| 16 | 2090728 |
| 17 | 5845015 |
| 18 | 16384908 |
| 19 | 45973701 |
| 20 | 128944042 |
| 21 | 361364501 |
| 22 | 1012168575 |
| 23 | 2834690172 |
| 24 | 7939970075 |
| 25 | 22244001961 |
| 26 | 62323608147 |
| 27 | 174620915138 |
| 28 | 489240430938 |
| 29 | 1370662332271 |
| 30 | 3839992876850 |