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 | 3 |
| 2 | 14 |
| 3 | 67 |
| 4 | 321 |
| 5 | 1538 |
| 6 | 7369 |
| 7 | 35307 |
| 8 | 169166 |
| 9 | 810523 |
| 10 | 3883449 |
| 11 | 18606722 |
| 12 | 89150161 |
| 13 | 427144083 |
| 14 | 2046570254 |
| 15 | 9805707187 |
| 16 | 46981965681 |
| 17 | 225104121218 |
| 18 | 1078538640409 |
| 19 | 5167589080827 |
| 20 | 24759406763726 |
| 21 | 118629444737803 |