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 | 10 |
| 5 | 40 |
| 6 | 90 |
| 7 | 230 |
| 8 | 570 |
| 9 | 1390 |
| 10 | 3360 |
| 11 | 8110 |
| 12 | 19600 |
| 13 | 47320 |
| 14 | 114240 |
| 15 | 275800 |
| 16 | 665850 |
| 17 | 1607520 |
| 18 | 3880890 |
| 19 | 9369310 |
| 20 | 22619530 |
| 21 | 54608390 |
| 22 | 131836320 |
| 23 | 318281030 |
| 24 | 768398400 |
| 25 | 1855077840 |
| 26 | 4478554080 |
| 27 | 10812186000 |
| 28 | 26102926090 |
| 29 | 63018038200 |