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 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 27 |
| 6 | 207 |
| 7 | 1689 |
| 8 | 17137 |
| 9 | 196869 |
| 10 | 2556856 |
| 11 | 36878013 |
| 12 | 585247590 |
| 13 | 10131891315 |
| 14 | 190024056601 |
| 15 | 3838053182983 |
| 16 | 83057105368627 |
| 17 | 1917217162193175 |
| 18 | 47021314781221603 |
| 19 | 1221073517359584357 |
| 20 | 33471097453271690668 |
| 21 | 965771726172667547339 |
| 22 | 29259595679585441629303 |