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 | -1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 9 |
| 5 | 11 |
| 6 | 17 |
| 7 | 59 |
| 8 | 237 |
| 9 | 849 |
| 10 | 2861 |
| 11 | 9625 |
| 12 | 33057 |
| 13 | 115753 |
| 14 | 410581 |
| 15 | 1469325 |
| 16 | 5296449 |
| 17 | 19216691 |
| 18 | 70134489 |
| 19 | 257320475 |
| 20 | 948545125 |
| 21 | 3511308899 |
| 22 | 13047504065 |
| 23 | 48649662439 |
| 24 | 181967395749 |
| 25 | 682578873479 |
| 26 | 2567177040641 |
| 27 | 9678602093387 |
| 28 | 36571567691029 |