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 | 0 |
| 1 | 6 |
| 2 | 52 |
| 3 | 411 |
| 4 | 3392 |
| 5 | 30070 |
| 6 | 287802 |
| 7 | 2969267 |
| 8 | 32902560 |
| 9 | 389989449 |
| 10 | 4924511300 |
| 11 | 65995764461 |
| 12 | 935412316380 |
| 13 | 13978234748257 |
| 14 | 219593721606826 |
| 15 | 3617245945896600 |
| 16 | 62330776215811680 |
| 17 | 1121143456571006754 |
| 18 | 21008889235589947362 |