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 | 1 |
| 2 | 6 |
| 3 | 24 |
| 4 | 74 |
| 5 | 220 |
| 6 | 626 |
| 7 | 1754 |
| 8 | 4860 |
| 9 | 13390 |
| 10 | 36762 |
| 11 | 100728 |
| 12 | 275666 |
| 13 | 753898 |
| 14 | 2060924 |
| 15 | 5632550 |
| 16 | 15391650 |
| 17 | 42056008 |
| 18 | 114907626 |
| 19 | 313947186 |
| 20 | 857741852 |
| 21 | 2343430222 |