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 | 6 |
| 3 | 72 |
| 4 | 1086 |
| 5 | 15076 |
| 6 | 182832 |
| 7 | 1957192 |
| 8 | 18583582 |
| 9 | 154252476 |
| 10 | 1166493640 |
| 11 | 8049232896 |
| 12 | 50660059120 |
| 13 | 292884155232 |
| 14 | 1582952988656 |
| 15 | 8045405614080 |
| 16 | 38559135542174 |
| 17 | 174391413419872 |
| 18 | 746859203235976 |
| 19 | 3047000304533760 |
| 20 | 11915800843394536 |
| 21 | 44815994695641600 |