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 | -2 |
| 1 | -1 |
| 2 | 12 |
| 3 | 81 |
| 4 | 378 |
| 5 | 1539 |
| 6 | 5832 |
| 7 | 21141 |
| 8 | 74358 |
| 9 | 255879 |
| 10 | 866052 |
| 11 | 2893401 |
| 12 | 9565938 |
| 13 | 31355019 |
| 14 | 102036672 |
| 15 | 330024861 |
| 16 | 1061819118 |
| 17 | 3400690959 |
| 18 | 10847773692 |
| 19 | 34480423521 |
| 20 | 109252577898 |
| 21 | 345191655699 |