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 | 5 |
| 4 | 23 |
| 5 | 123 |
| 6 | 700 |
| 7 | 4170 |
| 8 | 25677 |
| 9 | 162101 |
| 10 | 1043603 |
| 11 | 6825429 |
| 12 | 45222437 |
| 13 | 302892681 |
| 14 | 2047499720 |
| 15 | 13950769772 |
| 16 | 95710823820 |
| 17 | 660609751890 |
| 18 | 4584018016679 |
| 19 | 31960334260971 |
| 20 | 223782306725768 |
| 21 | 1572921720684820 |
| 22 | 11094267854522250 |
| 23 | 78499108540111380 |
| 24 | 557041048588402170 |