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 | 6 |
| 2 | 31 |
| 3 | 157 |
| 4 | 793 |
| 5 | 4004 |
| 6 | 20216 |
| 7 | 102069 |
| 8 | 515338 |
| 9 | 2601899 |
| 10 | 13136773 |
| 11 | 66326481 |
| 12 | 334876920 |
| 13 | 1690765888 |
| 14 | 8536537209 |
| 15 | 43100270734 |
| 16 | 217609704247 |
| 17 | 1098693409021 |
| 18 | 5547212203625 |
| 19 | 28007415880892 |
| 20 | 141407127676248 |