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 | 3 |
| 3 | 6 |
| 4 | 20 |
| 5 | 75 |
| 6 | 336 |
| 7 | 1708 |
| 8 | 9792 |
| 9 | 62325 |
| 10 | 436480 |
| 11 | 3334386 |
| 12 | 27595776 |
| 13 | 245951615 |
| 14 | 2348666880 |
| 15 | 23923317720 |
| 16 | 258910994432 |
| 17 | 2966901358185 |
| 18 | 35886973648896 |
| 19 | 456927138333790 |
| 20 | 6108665873694720 |
| 21 | 85555744482868275 |
| 22 | 1252729007440396288 |
| 23 | 19140289332506060676 |