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 | 3 |
| 3 | 13 |
| 4 | 49 |
| 5 | 261 |
| 6 | 1531 |
| 7 | 9073 |
| 8 | 63393 |
| 9 | 465769 |
| 10 | 3566611 |
| 11 | 29998101 |
| 12 | 262167313 |
| 13 | 2394499693 |
| 14 | 23249961099 |
| 15 | 233439305401 |
| 16 | 2439472944961 |
| 17 | 26649502709073 |
| 18 | 300078056044963 |
| 19 | 3498896317045789 |
| 20 | 42244252226263281 |
| 21 | 524289088799352661 |