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 | 21 |
| 3 | 195 |
| 4 | 2085 |
| 5 | 24243 |
| 6 | 297909 |
| 7 | 3806883 |
| 8 | 50082885 |
| 9 | 673851795 |
| 10 | 9229863381 |
| 11 | 128273819523 |
| 12 | 1804331883621 |
| 13 | 25639360102515 |
| 14 | 367507859864565 |
| 15 | 5307403512554595 |
| 16 | 77150495031376005 |
| 17 | 1127965980470739795 |
| 18 | 16575672566809158165 |
| 19 | 244695925293076974915 |