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 | 5 |
| 1 | 35 |
| 2 | 1260 |
| 3 | 4620 |
| 4 | 30030 |
| 5 | 90090 |
| 6 | 1021020 |
| 7 | 2771340 |
| 8 | 14549535 |
| 9 | 37182145 |
| 10 | 1487285800 |
| 11 | 3650610600 |
| 12 | 17644617900 |
| 13 | 42075627300 |
| 14 | 396713057400 |
| 15 | 925663800600 |
| 16 | 4281195077775 |
| 17 | 9821565178425 |
| 18 | 178970743251300 |
| 19 | 405039050516100 |
| 20 | 1822675727322450 |
| 21 | 4079321865912150 |