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 | 4 |
| 2 | 28 |
| 3 | 190 |
| 4 | 1216 |
| 5 | 7534 |
| 6 | 45928 |
| 7 | 277750 |
| 8 | 1673056 |
| 9 | 10058014 |
| 10 | 60407128 |
| 11 | 362619910 |
| 12 | 2176250896 |
| 13 | 13059099694 |
| 14 | 78359381128 |
| 15 | 470170635670 |
| 16 | 2821066860736 |
| 17 | 16926530304574 |
| 18 | 101559569247928 |
| 19 | 609358577749030 |
| 20 | 3656154953278576 |