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 | 0 |
| 2 | 10 |
| 3 | 50 |
| 4 | 250 |
| 5 | 1250 |
| 6 | 6250 |
| 7 | 31250 |
| 8 | 156250 |
| 9 | 781250 |
| 10 | 3906250 |
| 11 | 19531250 |
| 12 | 97656250 |
| 13 | 488281250 |
| 14 | 2441406250 |
| 15 | 12207031250 |
| 16 | 61035156250 |
| 17 | 305175781250 |
| 18 | 1525878906250 |
| 19 | 7629394531250 |
| 20 | 38146972656250 |
| 21 | 190734863281250 |