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 | 21 |
| 3 | 101 |
| 4 | 502 |
| 5 | 2502 |
| 6 | 12502 |
| 7 | 62503 |
| 8 | 312503 |
| 9 | 1562503 |
| 10 | 7812504 |
| 11 | 39062504 |
| 12 | 195312504 |
| 13 | 976562505 |
| 14 | 4882812505 |
| 15 | 24414062505 |
| 16 | 122070312506 |
| 17 | 610351562506 |
| 18 | 3051757812506 |
| 19 | 15258789062507 |
| 20 | 76293945312507 |
| 21 | 381469726562507 |