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 | 0 |
| 3 | 1 |
| 4 | 16 |
| 5 | 257 |
| 6 | 5636 |
| 7 | 187432 |
| 8 | 9956054 |
| 9 | 867875816 |
| 10 | 125861715682 |
| 11 | 30575624363575 |
| 12 | 12486657463326416 |
| 13 | 8588874417105963246 |
| 14 | 9960958211434474577452 |
| 15 | 19489076635898035234022220 |
| 16 | 64349049302453152886635937502 |
| 17 | 358611453994361731825817399132622 |
| 18 | 3373425033361375072576454177693810076 |