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 | 3 |
| 2 | 3 |
| 3 | 9 |
| 4 | 36 |
| 5 | 108 |
| 6 | 351 |
| 7 | 1053 |
| 8 | 3240 |
| 9 | 9720 |
| 10 | 29403 |
| 11 | 88209 |
| 12 | 265356 |
| 13 | 796068 |
| 14 | 2390391 |
| 15 | 7171173 |
| 16 | 21520080 |
| 17 | 64560240 |
| 18 | 193700403 |
| 19 | 581101209 |
| 20 | 1743362676 |
| 21 | 5230088028 |
| 22 | 15690441231 |
| 23 | 47071323693 |
| 24 | 141214502520 |
| 25 | 423643507560 |