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) |
|---|---|
| 1 | 4 |
| 2 | 13 |
| 3 | 40 |
| 4 | 130 |
| 5 | 400 |
| 6 | 1300 |
| 7 | 4000 |
| 8 | 13000 |
| 9 | 40000 |
| 10 | 130000 |
| 11 | 400000 |
| 12 | 1300000 |
| 13 | 4000000 |
| 14 | 13000000 |
| 15 | 40000000 |
| 16 | 130000000 |
| 17 | 400000000 |
| 18 | 1300000000 |
| 19 | 4000000000 |
| 20 | 13000000000 |
| 21 | 40000000000 |
| 22 | 130000000000 |
| 23 | 400000000000 |
| 24 | 1300000000000 |