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 | 5 |
| 4 | 20 |
| 5 | 97 |
| 6 | 573 |
| 7 | 3956 |
| 8 | 31285 |
| 9 | 278721 |
| 10 | 2761871 |
| 11 | 30129503 |
| 12 | 358814994 |
| 13 | 4631975383 |
| 14 | 64426566695 |
| 15 | 960541539816 |
| 16 | 15281342678897 |
| 17 | 258393612570435 |
| 18 | 4627594697852333 |
| 19 | 87503608832116847 |
| 20 | 1742117303112144502 |