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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 14 |
| 5 | 75 |
| 6 | 454 |
| 7 | 3185 |
| 8 | 25486 |
| 9 | 229383 |
| 10 | 2293838 |
| 11 | 25232229 |
| 12 | 302786758 |
| 13 | 3936227867 |
| 14 | 55107190150 |
| 15 | 826607852265 |
| 16 | 13225725636254 |
| 17 | 224837335816335 |
| 18 | 4047072044694046 |
| 19 | 76894368849186893 |
| 20 | 1537887376983737878 |