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 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 198 |
| 7 | 793 |
| 8 | 3255 |
| 9 | 13529 |
| 10 | 56696 |
| 11 | 239340 |
| 12 | 1017900 |
| 13 | 4361840 |
| 14 | 18828606 |
| 15 | 81833505 |
| 16 | 357865215 |
| 17 | 1573549667 |
| 18 | 6952392450 |
| 19 | 30848928525 |
| 20 | 137403484655 |
| 21 | 614104910096 |
| 22 | 2753200345000 |
| 23 | 12378494389660 |
| 24 | 55799811151140 |
| 25 | 252141767612812 |
| 26 | 1141894552992368 |