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 | 15 |
| 3 | 169 |
| 4 | 2255 |
| 5 | 30381 |
| 6 | 418503 |
| 7 | 5832765 |
| 8 | 82073295 |
| 9 | 1163205475 |
| 10 | 16581420835 |
| 11 | 237481736823 |
| 12 | 3414582082055 |
| 13 | 49258226347903 |
| 14 | 712601187601395 |
| 15 | 10334165623697259 |
| 16 | 150186639579545295 |
| 17 | 2186774434431445455 |
| 18 | 31893473567409732813 |
| 19 | 465851764737061437765 |