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 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 8 |
| 6 | 24 |
| 7 | 74 |
| 8 | 246 |
| 9 | 848 |
| 10 | 3088 |
| 11 | 11644 |
| 12 | 45844 |
| 13 | 186336 |
| 14 | 784928 |
| 15 | 3403128 |
| 16 | 15212744 |
| 17 | 69802944 |
| 18 | 328988096 |
| 19 | 1587831568 |
| 20 | 7848954928 |
| 21 | 39651793024 |
| 22 | 204691645824 |
| 23 | 1078028406176 |
| 24 | 5790745961568 |
| 25 | 31687186373888 |
| 26 | 176575788105984 |
| 27 | 1001061518465984 |
| 28 | 5771865641210176 |