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 | 1 |
| 2 | 9 |
| 3 | 90 |
| 4 | 1015 |
| 5 | 12978 |
| 6 | 187110 |
| 7 | 3008148 |
| 8 | 53275365 |
| 9 | 1028142830 |
| 10 | 21426984722 |
| 11 | 478684639524 |
| 12 | 11394222257054 |
| 13 | 287518726261900 |
| 14 | 7658231720886900 |
| 15 | 214521099685649640 |
| 16 | 6299407928673657135 |
| 17 | 193373975592937777770 |
| 18 | 6189939300880260745050 |
| 19 | 206159811915115686404700 |