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 | 8 |
| 2 | 56 |
| 3 | 392 |
| 4 | 2648 |
| 5 | 17960 |
| 6 | 120056 |
| 7 | 804824 |
| 8 | 5351720 |
| 9 | 35652680 |
| 10 | 236291096 |
| 11 | 1568049560 |
| 12 | 10368669992 |
| 13 | 68626647608 |
| 14 | 453032542040 |
| 15 | 2992783648424 |
| 16 | 19731335857592 |
| 17 | 130161040083608 |
| 18 | 857282278813256 |
| 19 | 5648892048530888 |
| 20 | 37175039569217672 |
| 21 | 244738250638121768 |