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 | 6 |
| 2 | 15 |
| 3 | 70 |
| 4 | 105 |
| 5 | 2310 |
| 6 | 5005 |
| 7 | 30030 |
| 8 | 255255 |
| 9 | 3233230 |
| 10 | 969969 |
| 11 | 44618574 |
| 12 | 37182145 |
| 13 | 223092870 |
| 14 | 3234846615 |
| 15 | 66853496710 |
| 16 | 100280245065 |
| 17 | 200560490130 |
| 18 | 1236789689135 |
| 19 | 7420738134810 |
| 20 | 30425026352721 |