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 | 6 |
| 2 | 30 |
| 3 | 186 |
| 4 | 1290 |
| 5 | 9582 |
| 6 | 74550 |
| 7 | 599730 |
| 8 | 4948050 |
| 9 | 41638614 |
| 10 | 356007630 |
| 11 | 3083837802 |
| 12 | 27006251610 |
| 13 | 238704231102 |
| 14 | 2126733078630 |
| 15 | 19079571337314 |
| 16 | 172209370246050 |
| 17 | 1562686251141030 |
| 18 | 14248144422407550 |
| 19 | 130467052593799962 |