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 | 2 |
| 2 | 0 |
| 3 | 5 |
| 4 | 0 |
| 5 | 18 |
| 6 | 0 |
| 7 | 58 |
| 8 | 0 |
| 9 | 160 |
| 10 | 0 |
| 11 | 795 |
| 12 | 0 |
| 13 | 3167 |
| 14 | 0 |
| 15 | 13519 |
| 16 | 0 |
| 17 | 60829 |
| 18 | 0 |
| 19 | 270693 |
| 20 | 0 |
| 21 | 1177412 |
| 22 | 0 |
| 23 | 5502114 |
| 24 | 0 |
| 25 | 25026242 |
| 26 | 0 |
| 27 | 114884910 |
| 28 | 0 |