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 | 20 |
| 3 | 100 |
| 4 | 600 |
| 5 | 3000 |
| 6 | 15500 |
| 7 | 77500 |
| 8 | 390000 |
| 9 | 1950000 |
| 10 | 9762500 |
| 11 | 48812500 |
| 12 | 244125000 |
| 13 | 1220625000 |
| 14 | 6103437500 |
| 15 | 30517187500 |
| 16 | 152587500000 |
| 17 | 762937500000 |
| 18 | 3814695312500 |
| 19 | 19073476562500 |
| 20 | 95367421875000 |
| 21 | 476837109375000 |
| 22 | 2384185742187500 |
| 23 | 11920928710937500 |
| 24 | 59604644531250000 |
| 25 | 298023222656250000 |