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 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 16 |
| 5 | 64 |
| 6 | 416 |
| 7 | 2848 |
| 8 | 22912 |
| 9 | 205952 |
| 10 | 2060032 |
| 11 | 22659328 |
| 12 | 271913984 |
| 13 | 3534877696 |
| 14 | 49488295936 |
| 15 | 742324422656 |
| 16 | 11877190795264 |
| 17 | 201912243453952 |
| 18 | 3634420382302208 |
| 19 | 69053987263479808 |
| 20 | 1381079745270120448 |
| 21 | 29002674650671480832 |
| 22 | 638058842314774675456 |