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 | 3 |
| 1 | 11 |
| 2 | 45 |
| 3 | 197 |
| 4 | 897 |
| 5 | 4181 |
| 6 | 19785 |
| 7 | 94637 |
| 8 | 456417 |
| 9 | 2215781 |
| 10 | 10815225 |
| 11 | 53024477 |
| 12 | 260921937 |
| 13 | 1287820181 |
| 14 | 6371967465 |
| 15 | 31591352717 |
| 16 | 156882923457 |
| 17 | 780119453381 |
| 18 | 3883417004505 |
| 19 | 19348364759357 |
| 20 | 96466944316977 |
| 21 | 481235206811381 |