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 | 4 |
| 5 | 13 |
| 6 | 42 |
| 7 | 119 |
| 8 | 330 |
| 9 | 890 |
| 10 | 2376 |
| 11 | 6291 |
| 12 | 16588 |
| 13 | 43615 |
| 14 | 114492 |
| 15 | 300236 |
| 16 | 786828 |
| 17 | 2061233 |
| 18 | 5398470 |
| 19 | 14136759 |
| 20 | 37015990 |
| 21 | 96917974 |
| 22 | 253748880 |
| 23 | 664346375 |
| 24 | 1739318904 |
| 25 | 4553656703 |
| 26 | 11921726232 |
| 27 | 31211643384 |
| 28 | 81713400340 |
| 29 | 213928875445 |
| 30 | 560073740226 |