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) |
|---|---|
| 4 | 6 |
| 5 | 50 |
| 6 | 262 |
| 7 | 1114 |
| 8 | 4278 |
| 9 | 15769 |
| 10 | 58147 |
| 11 | 221089 |
| 12 | 886411 |
| 13 | 3806475 |
| 14 | 17681979 |
| 15 | 89337562 |
| 16 | 492188528 |
| 17 | 2959459154 |
| 18 | 19424078142 |
| 19 | 139141985438 |
| 20 | 1087614361775 |
| 21 | 9274721292503 |