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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 47 |
| 5 | 447 |
| 6 | 2163 |
| 7 | 24263 |
| 8 | 241727 |
| 9 | 2923783 |
| 10 | 16485763 |
| 11 | 169053487 |
| 12 | 4535472963 |
| 13 | 36316463227 |
| 14 | 879728844873 |
| 15 | 4476534430363 |
| 16 | 119919330795347 |
| 17 | 1374445897718223 |
| 18 | 106298577886531087 |