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 | 15 |
| 2 | 180 |
| 3 | 1980 |
| 4 | 20790 |
| 5 | 212058 |
| 6 | 2120580 |
| 7 | 20902860 |
| 8 | 203802885 |
| 9 | 1970094555 |
| 10 | 18912907728 |
| 11 | 180532301040 |
| 12 | 1715056859880 |
| 13 | 16227076443480 |
| 14 | 152998149324240 |
| 15 | 1438182603647856 |
| 16 | 13482961909198650 |
| 17 | 126105349621328550 |
| 18 | 1176983263132399800 |
| 19 | 10964528293391303400 |
| 20 | 101970113128539121620 |