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 | 55 |
| 2 | 1210 |
| 3 | 15730 |
| 4 | 143143 |
| 5 | 1002001 |
| 6 | 5725720 |
| 7 | 27810640 |
| 8 | 118195220 |
| 9 | 449141836 |
| 10 | 1551580888 |
| 11 | 4936848280 |
| 12 | 14620666060 |
| 13 | 40648664980 |
| 14 | 106847919376 |
| 15 | 267119798440 |
| 16 | 638337753625 |
| 17 | 1464421905375 |
| 18 | 3237143159250 |
| 19 | 6917263803450 |