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 | 3 |
| 2 | 12 |
| 3 | 63 |
| 4 | 408 |
| 5 | 3123 |
| 6 | 27552 |
| 7 | 275103 |
| 8 | 3065088 |
| 9 | 37682883 |
| 10 | 506606592 |
| 11 | 7392091743 |
| 12 | 116329479168 |
| 13 | 1963781841843 |
| 14 | 35395627487232 |
| 15 | 678401549017983 |
| 16 | 13776623985819648 |
| 17 | 295481239628640003 |
| 18 | 6674320861079273472 |
| 19 | 158364407589097613823 |
| 20 | 3937958237874411798528 |