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 | 15 |
| 2 | 25 |
| 3 | 75 |
| 4 | 275 |
| 5 | 725 |
| 6 | 2175 |
| 7 | 3725 |
| 8 | 9025 |
| 9 | 27075 |
| 10 | 79025 |
| 11 | 215905 |
| 12 | 390625 |
| 13 | 1079525 |
| 14 | 2256125 |
| 15 | 5397625 |
| 16 | 11328125 |
| 17 | 33984375 |
| 18 | 58203125 |
| 19 | 174609375 |