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 | 6 |
| 2 | 30 |
| 3 | 150 |
| 4 | 750 |
| 5 | 3750 |
| 6 | 18750 |
| 7 | 93750 |
| 8 | 468750 |
| 9 | 2343750 |
| 10 | 11718750 |
| 11 | 58593750 |
| 12 | 292968750 |
| 13 | 1464843750 |
| 14 | 7324218750 |
| 15 | 36621093735 |
| 16 | 183105468600 |
| 17 | 915527342640 |
| 18 | 4577636711400 |
| 19 | 22888183548000 |
| 20 | 114440917695000 |
| 21 | 572204588250000 |