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 | 6 |
| 2 | 69 |
| 3 | 992 |
| 4 | 15990 |
| 5 | 276360 |
| 6 | 5006386 |
| 7 | 93817152 |
| 8 | 1803606255 |
| 9 | 35373572460 |
| 10 | 704995403541 |
| 11 | 14236901646240 |
| 12 | 290687378847684 |
| 13 | 5990903682047592 |
| 14 | 124463414269524000 |
| 15 | 2603845580096662656 |
| 16 | 54807372993836345589 |
| 17 | 1159856934027109448130 |
| 18 | 24663454505518980363102 |
| 19 | 526708243449729452311200 |
| 20 | 11291926596343014148087470 |