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 | 5 |
| 2 | 30 |
| 3 | 155 |
| 4 | 805 |
| 5 | 4055 |
| 6 | 20455 |
| 7 | 102455 |
| 8 | 513230 |
| 9 | 2567230 |
| 10 | 12841130 |
| 11 | 64211380 |
| 12 | 321082905 |
| 13 | 1605444405 |
| 14 | 8027354055 |
| 15 | 40136925680 |
| 16 | 200685295955 |
| 17 | 1003427268205 |
| 18 | 5017139711105 |
| 19 | 25085702537730 |
| 20 | 125428529603755 |
| 21 | 627142668099880 |
| 22 | 3135713425289030 |
| 23 | 15678567227192655 |