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 | 3 |
| 2 | 9 |
| 3 | 29 |
| 4 | 96 |
| 5 | 321 |
| 6 | 1077 |
| 7 | 3617 |
| 8 | 12149 |
| 9 | 40802 |
| 10 | 137009 |
| 11 | 459991 |
| 12 | 1544169 |
| 13 | 5183201 |
| 14 | 17396800 |
| 15 | 58387097 |
| 16 | 195950657 |
| 17 | 657602545 |
| 18 | 2206838633 |
| 19 | 7405775266 |
| 20 | 24852220929 |
| 21 | 83398067755 |
| 22 | 279861976377 |
| 23 | 939138581941 |
| 24 | 3151475258656 |
| 25 | 10575403936625 |
| 26 | 35487807890381 |