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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 44 |
| 5 | 361 |
| 6 | 3654 |
| 7 | 44207 |
| 8 | 622552 |
| 9 | 10005041 |
| 10 | 180713290 |
| 11 | 3624270839 |
| 12 | 79914671748 |
| 13 | 1921576392793 |
| 14 | 50040900884366 |
| 15 | 1403066801155039 |
| 16 | 42142044935535536 |
| 17 | 1349948504738292193 |
| 18 | 45940391206037470098 |