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 | 8 |
| 3 | 57 |
| 4 | 407 |
| 5 | 2906 |
| 6 | 20749 |
| 7 | 148149 |
| 8 | 1057792 |
| 9 | 7552693 |
| 10 | 53926643 |
| 11 | 385039194 |
| 12 | 2749201001 |
| 13 | 19629446201 |
| 14 | 140155324408 |
| 15 | 1000716717057 |
| 16 | 7145172343807 |
| 17 | 51016923123706 |
| 18 | 364263634209749 |
| 19 | 2600862362591949 |
| 20 | 18570300172353392 |