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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 21 |
| 5 | 966 |
| 6 | 27954 |
| 7 | 650076 |
| 8 | 13271982 |
| 9 | 248371380 |
| 10 | 4366441128 |
| 11 | 73231116024 |
| 12 | 1183803697278 |
| 13 | 18579191525700 |
| 14 | 284601154513452 |
| 15 | 4272100949982600 |
| 16 | 63034617139799916 |
| 17 | 916440476048146056 |
| 18 | 13154166812674577412 |
| 19 | 186700695099591735024 |
| 20 | 2623742783421329300190 |
| 21 | 36548087103760045010148 |
| 22 | 505099724454854883618924 |