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 | 4 |
| 2 | 21 |
| 3 | 156 |
| 4 | 1540 |
| 5 | 19160 |
| 6 | 288813 |
| 7 | 5123608 |
| 8 | 104657520 |
| 9 | 2420186616 |
| 10 | 62514944778 |
| 11 | 1784255891484 |
| 12 | 55767065855228 |
| 13 | 1894463658611680 |
| 14 | 69504774168222109 |
| 15 | 2738952451360200312 |
| 16 | 115380142451625516088 |
| 17 | 5174227834995200591840 |