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 | 0 |
| 2 | 6 |
| 3 | 16 |
| 4 | 39 |
| 5 | 270 |
| 6 | 1592 |
| 7 | 12042 |
| 8 | 75739 |
| 9 | 490425 |
| 10 | 3084820 |
| 11 | 19634393 |
| 12 | 129519588 |
| 13 | 829432020 |
| 14 | 5341866361 |
| 15 | 34667291397 |
| 16 | 223006749453 |
| 17 | 1438573920539 |
| 18 | 9290258941352 |
| 19 | 59927615962595 |
| 20 | 386783857393798 |
| 21 | 2495707675837699 |