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 | 1 |
| 3 | 7 |
| 4 | 49 |
| 5 | 181 |
| 6 | 1201 |
| 7 | 16171 |
| 8 | 122977 |
| 9 | 971209 |
| 10 | 16788961 |
| 11 | 206578351 |
| 12 | 2094314641 |
| 13 | 40260673597 |
| 14 | 694617709969 |
| 15 | 9088535091091 |
| 16 | 187060085419201 |
| 17 | 4109646055718161 |
| 18 | 68029103349383617 |
| 19 | 1498126927153125079 |
| 20 | 39199612737165358321 |
| 21 | 799248202624341298501 |