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 | 3 |
| 3 | 13 |
| 4 | 68 |
| 5 | 399 |
| 6 | 2530 |
| 7 | 16965 |
| 8 | 118668 |
| 9 | 857956 |
| 10 | 6369883 |
| 11 | 48336171 |
| 12 | 373537388 |
| 13 | 2931682810 |
| 14 | 23317105140 |
| 15 | 187606350645 |
| 16 | 1524813969276 |
| 17 | 12504654858828 |
| 18 | 103367824774012 |
| 19 | 860593023907540 |
| 20 | 7211115497448720 |
| 21 | 60776550501588855 |