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 | 3 |
| 5 | 11 |
| 6 | 56 |
| 7 | 385 |
| 8 | 3994 |
| 9 | 67014 |
| 10 | 1973029 |
| 11 | 105731474 |
| 12 | 10439496931 |
| 13 | 1902968718515 |
| 14 | 641662974453892 |
| 15 | 401490336727861176 |
| 16 | 467924684115578671326 |
| 17 | 1019752390010650509117288 |
| 18 | 4171131179469162937375841939 |
| 19 | 32134378048921787829834095722663 |
| 20 | 467778894124037894839737804918978194 |