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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 44 |
| 6 | 168 |
| 7 | 536 |
| 8 | 1661 |
| 9 | 5328 |
| 10 | 18129 |
| 11 | 62592 |
| 12 | 214657 |
| 13 | 726614 |
| 14 | 2438656 |
| 15 | 8192120 |
| 16 | 27614544 |
| 17 | 93315688 |
| 18 | 315490856 |
| 19 | 1065719578 |
| 20 | 3597204049 |
| 21 | 12138879608 |
| 22 | 40968868129 |
| 23 | 138302514360 |
| 24 | 466929286109 |
| 25 | 1576394674460 |
| 26 | 5321736915096 |
| 27 | 17964911573280 |
| 28 | 60645076322201 |