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) |
|---|---|
| 2 | 3 |
| 3 | 6 |
| 4 | 15 |
| 5 | 45 |
| 6 | 153 |
| 7 | 561 |
| 8 | 2145 |
| 9 | 8385 |
| 10 | 33153 |
| 11 | 131841 |
| 12 | 525825 |
| 13 | 2100225 |
| 14 | 8394753 |
| 15 | 33566721 |
| 16 | 134242305 |
| 17 | 536920065 |
| 18 | 2147581953 |
| 19 | 8590131201 |
| 20 | 34360131585 |
| 21 | 137439739905 |
| 22 | 549757386753 |
| 23 | 2199026401281 |
| 24 | 8796099313665 |
| 25 | 35184384671745 |