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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 15 |
| 5 | 7 |
| 6 | 35 |
| 7 | 165 |
| 8 | 1001 |
| 9 | 5005 |
| 10 | 51051 |
| 11 | 20995 |
| 12 | 1616615 |
| 13 | 1716099 |
| 14 | 5311735 |
| 15 | 7436429 |
| 16 | 3234846615 |
| 17 | 178752665 |
| 18 | 955049953 |
| 19 | 5277907635 |
| 20 | 19027533679 |
| 21 | 176684241305 |
| 22 | 13829557433055 |
| 23 | 18960523669087 |
| 24 | 2180460221945005 |
| 25 | 8784139751264163 |
| 26 | 463717784757535 |
| 27 | 102481630431415235 |