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 | 5 |
| 2 | 55 |
| 3 | 305 |
| 4 | 2255 |
| 5 | 15005 |
| 6 | 104005 |
| 7 | 709805 |
| 8 | 4873055 |
| 9 | 33379505 |
| 10 | 228841255 |
| 11 | 1568358005 |
| 12 | 10750060805 |
| 13 | 73681030805 |
| 14 | 505019869255 |
| 15 | 3461450947505 |
| 16 | 23725155368255 |
| 17 | 162614587921805 |
| 18 | 1114577087604805 |
| 19 | 7639424691459005 |
| 20 | 52361396626646255 |
| 21 | 358890349406803505 |