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) |
|---|---|
| 1 | 6 |
| 2 | 31 |
| 3 | 144 |
| 4 | 621 |
| 5 | 2538 |
| 6 | 9963 |
| 7 | 37908 |
| 8 | 140697 |
| 9 | 511758 |
| 10 | 1830519 |
| 11 | 6456024 |
| 12 | 22497669 |
| 13 | 77590386 |
| 14 | 265189059 |
| 15 | 899198172 |
| 16 | 3027619377 |
| 17 | 10130328342 |
| 18 | 33705582543 |
| 19 | 111577100832 |
| 20 | 367662044061 |
| 21 | 1206427402746 |
| 22 | 3943553157531 |
| 23 | 12845313733284 |