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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 10 |
| 6 | 34 |
| 7 | 272 |
| 8 | 3528 |
| 9 | 97144 |
| 10 | 4870920 |
| 11 | 452016608 |
| 12 | 77054901728 |
| 13 | 24271105072736 |
| 14 | 14200712295904928 |
| 15 | 15510501136026729216 |
| 16 | 31765207922047709885696 |
| 17 | 122456389219489134370435456 |
| 18 | 891699423142395494501906828160 |
| 19 | 12302820585630191716774996205431296 |