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 | 4 |
| 3 | 4 |
| 4 | 28 |
| 5 | 64 |
| 6 | 268 |
| 7 | 844 |
| 8 | 3100 |
| 9 | 10876 |
| 10 | 39244 |
| 11 | 142432 |
| 12 | 518380 |
| 13 | 1906012 |
| 14 | 7012660 |
| 15 | 25980940 |
| 16 | 96407356 |
| 17 | 359260936 |
| 18 | 1341482740 |
| 19 | 5023006444 |
| 20 | 18844637356 |