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 | 2 |
| 3 | 4 |
| 4 | 18 |
| 5 | 72 |
| 6 | 396 |
| 7 | 2328 |
| 8 | 17050 |
| 9 | 131764 |
| 10 | 1199368 |
| 11 | 11379524 |
| 12 | 123012492 |
| 13 | 1386127700 |
| 14 | 17450444866 |
| 15 | 227152227940 |