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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 16 |
| 6 | 78 |
| 7 | 522 |
| 8 | 6168 |
| 9 | 137316 |
| 10 | 6002584 |
| 11 | 509498932 |
| 12 | 82545585936 |
| 13 | 25251015681176 |
| 14 | 14527077828617744 |
| 15 | 15713242984902154384 |
| 16 | 32000507852263778595584 |
| 17 | 122967932076766466336249888 |
| 18 | 893788862572805850273939095424 |
| 19 | 12318904626562502262191503745716384 |