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 | 17 |
| 3 | 105 |
| 4 | 671 |
| 5 | 4393 |
| 6 | 29249 |
| 7 | 197117 |
| 8 | 1340579 |
| 9 | 9182013 |
| 10 | 63247587 |
| 11 | 437684991 |
| 12 | 3040564703 |
| 13 | 21191554941 |
| 14 | 148109893057 |
| 15 | 1037660903785 |
| 16 | 7285259590495 |
| 17 | 51244141331581 |
| 18 | 361046057274899 |
| 19 | 2547558161041995 |
| 20 | 17999651555835001 |