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 | 3 |
| 1 | 19 |
| 2 | 99 |
| 3 | 499 |
| 4 | 2499 |
| 5 | 12499 |
| 6 | 62499 |
| 7 | 312499 |
| 8 | 1562499 |
| 9 | 7812499 |
| 10 | 39062499 |
| 11 | 195312499 |
| 12 | 976562499 |
| 13 | 4882812499 |
| 14 | 24414062499 |
| 15 | 122070312499 |
| 16 | 610351562499 |
| 17 | 3051757812499 |
| 18 | 15258789062499 |
| 19 | 76293945312499 |
| 20 | 381469726562499 |
| 21 | 1907348632812499 |