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 | 5 |
| 2 | 15 |
| 3 | 45 |
| 4 | 140 |
| 5 | 441 |
| 6 | 1382 |
| 7 | 4322 |
| 8 | 13511 |
| 9 | 42238 |
| 10 | 132051 |
| 11 | 412840 |
| 12 | 1290698 |
| 13 | 4035218 |
| 14 | 12615643 |
| 15 | 39441343 |
| 16 | 123308779 |
| 17 | 385510576 |
| 18 | 1205254047 |
| 19 | 3768086810 |
| 20 | 11780485818 |
| 21 | 36830320820 |
| 22 | 115145720853 |
| 23 | 359989724116 |
| 24 | 1125466066030 |
| 25 | 3518638952555 |