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 | 2 |
| 3 | 6 |
| 4 | 28 |
| 5 | 177 |
| 6 | 1449 |
| 7 | 14869 |
| 8 | 185230 |
| 9 | 2738962 |
| 10 | 47287352 |
| 11 | 939759621 |
| 12 | 21241309681 |
| 13 | 540698975061 |
| 14 | 15370957337418 |
| 15 | 484433735633218 |
| 16 | 16817886069720724 |
| 17 | 639545680226171989 |
| 18 | 26507567678760284105 |