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 | 3 |
| 2 | 13 |
| 3 | 81 |
| 4 | 673 |
| 5 | 6993 |
| 6 | 87193 |
| 7 | 1268361 |
| 8 | 21086113 |
| 9 | 394368993 |
| 10 | 8195330473 |
| 11 | 187336699641 |
| 12 | 4671623344753 |
| 13 | 126204511859793 |
| 14 | 3671695236949753 |
| 15 | 114451527759954921 |
| 16 | 3805443567253430593 |
| 17 | 134436722612325267393 |
| 18 | 5028681509898733705033 |
| 19 | 198550708258762398282201 |