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 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 171 |
| 5 | 1552 |
| 6 | 16583 |
| 7 | 203443 |
| 8 | 2813660 |
| 9 | 43258011 |
| 10 | 731183365 |
| 11 | 13466814110 |
| 12 | 268270250977 |
| 13 | 5744515120489 |
| 14 | 131525839441428 |
| 15 | 3205279987587275 |
| 16 | 82812074976214547 |
| 17 | 2260364854328771548 |
| 18 | 64979726427408468055 |
| 19 | 1961976154991285214707 |
| 20 | 62065551492895731512852 |