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 | 4 |
| 3 | 15 |
| 4 | 21 |
| 5 | 45 |
| 6 | 75 |
| 7 | 465 |
| 8 | 1095 |
| 9 | 2145 |
| 10 | 4935 |
| 11 | 14955 |
| 12 | 80685 |
| 13 | 229845 |
| 14 | 1295325 |
| 15 | 1575285 |
| 16 | 9700575 |
| 17 | 20435415 |
| 18 | 15054105 |
| 19 | 53999715 |
| 20 | 2282745465 |