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 | 0 |
| 2 | 6 |
| 3 | 9 |
| 4 | 156 |
| 5 | 735 |
| 6 | 9738 |
| 7 | 83181 |
| 8 | 1129656 |
| 9 | 13662459 |
| 10 | 207281190 |
| 11 | 3151269033 |
| 12 | 54457383060 |
| 13 | 980680471095 |
| 14 | 19240001086530 |
| 15 | 397345461622245 |
| 16 | 8763618490102128 |
| 17 | 203472380293912563 |
| 18 | 4991552271140255838 |
| 19 | 128517790560854181537 |
| 20 | 3472936316648987980620 |