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 | 3 |
| 2 | 11 |
| 3 | 46 |
| 4 | 180 |
| 5 | 707 |
| 6 | 2729 |
| 7 | 10377 |
| 8 | 39045 |
| 9 | 145493 |
| 10 | 537749 |
| 11 | 1973915 |
| 12 | 7202499 |
| 13 | 26144901 |
| 14 | 94475783 |
| 15 | 340028026 |
| 16 | 1219451204 |
| 17 | 4359473611 |
| 18 | 15540448583 |
| 19 | 55255188413 |
| 20 | 196004642045 |
| 21 | 693798921723 |
| 22 | 2451058691129 |
| 23 | 8643625483966 |