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 | 2 |
| 2 | 12 |
| 3 | 74 |
| 4 | 456 |
| 5 | 2810 |
| 6 | 17316 |
| 7 | 106706 |
| 8 | 657552 |
| 9 | 4052018 |
| 10 | 24969660 |
| 11 | 153869978 |
| 12 | 948189528 |
| 13 | 5843007146 |
| 14 | 36006232404 |
| 15 | 221880401570 |
| 16 | 1367288641824 |
| 17 | 8425612252514 |
| 18 | 51920962156908 |
| 19 | 319951385193962 |
| 20 | 1971629273320680 |