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 | 1 |
| 2 | 3 |
| 3 | 30 |
| 4 | 175 |
| 5 | 4410 |
| 6 | 29106 |
| 7 | 396396 |
| 8 | 2760615 |
| 9 | 156434850 |
| 10 | 1122854590 |
| 11 | 16291599324 |
| 12 | 119224885962 |
| 13 | 3515605611700 |
| 14 | 26077294372500 |
| 15 | 388924218927000 |
| 16 | 2913690606794775 |
| 17 | 350671234206006450 |
| 18 | 2647224022927695750 |
| 19 | 40095381399899017500 |
| 20 | 304513870316075169750 |