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 | 3 |
| 2 | 25 |
| 3 | 225 |
| 4 | 2129 |
| 5 | 20723 |
| 6 | 205471 |
| 7 | 2063890 |
| 8 | 20931585 |
| 9 | 213864939 |
| 10 | 2198044805 |
| 11 | 22699471171 |
| 12 | 235354244255 |
| 13 | 2448409104820 |
| 14 | 25544033624414 |
| 15 | 267158874185420 |
| 16 | 2800191197529633 |
| 17 | 29405702263792875 |
| 18 | 309320021637262225 |
| 19 | 3258658594126096867 |
| 20 | 34376186445159365709 |