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 | 22 |
| 3 | 148 |
| 4 | 1144 |
| 5 | 9784 |
| 6 | 90346 |
| 7 | 885868 |
| 8 | 9115276 |
| 9 | 97578688 |
| 10 | 1079676448 |
| 11 | 12285725632 |
| 12 | 143204046496 |
| 13 | 1704422018992 |
| 14 | 20660609113186 |
| 15 | 254522834851516 |
| 16 | 3180935346538684 |
| 17 | 40269426101933392 |
| 18 | 515743456513546072 |
| 19 | 6675036087017279056 |
| 20 | 87221496402779437696 |
| 21 | 1149701868292524559744 |