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 | 2 |
| 3 | 11 |
| 4 | 87 |
| 5 | 952 |
| 6 | 13513 |
| 7 | 237113 |
| 8 | 5016728 |
| 9 | 125121009 |
| 10 | 3615047527 |
| 11 | 119384499720 |
| 12 | 4455637803543 |
| 13 | 186152008588691 |
| 14 | 8636436319397292 |
| 15 | 441871067839416319 |
| 16 | 24781002306869712365 |
| 17 | 1515279889256750470086 |
| 18 | 100546673139756241189021 |