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 | 4 |
| 2 | 25 |
| 3 | 121 |
| 4 | 568 |
| 5 | 2144 |
| 6 | 8231 |
| 7 | 27473 |
| 8 | 92244 |
| 9 | 279241 |
| 10 | 831581 |
| 11 | 2284733 |
| 12 | 6118941 |
| 13 | 15465573 |
| 14 | 37720667 |
| 15 | 88273017 |
| 16 | 197300906 |
| 17 | 429114775 |
| 18 | 881951878 |
| 19 | 1784140720 |
| 20 | 3373100313 |
| 21 | 6336692489 |
| 22 | 11005448210 |
| 23 | 19131647821 |
| 24 | 30415473928 |
| 25 | 48633111249 |