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 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 1 |
| 8 | 3 |
| 9 | 9 |
| 10 | 29 |
| 11 | 99 |
| 12 | 357 |
| 13 | 1350 |
| 14 | 5334 |
| 15 | 21912 |
| 16 | 93352 |
| 17 | 410988 |
| 18 | 1866492 |
| 19 | 8720924 |
| 20 | 41866020 |
| 21 | 206085480 |
| 22 | 1039120104 |
| 23 | 5358418224 |
| 24 | 28235017104 |
| 25 | 151838491408 |
| 26 | 832730775888 |
| 27 | 4652886489840 |
| 28 | 26470731088016 |
| 29 | 153207256585824 |
| 30 | 901628675631456 |
| 31 | 5391563546317056 |