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 | 2 |
| 3 | 8 |
| 4 | 63 |
| 5 | 893 |
| 6 | 19714 |
| 7 | 597510 |
| 8 | 22903403 |
| 9 | 1056115331 |
| 10 | 56744710974 |
| 11 | 3475626211316 |
| 12 | 238818544070905 |
| 13 | 18183183610029003 |
| 14 | 1519020289266947462 |
| 15 | 138117136134012654182 |
| 16 | 13576724206357958780409 |
| 17 | 1434561741418662640589225 |
| 18 | 162136032834834405685977058 |
| 19 | 19516966563322659948894106704 |