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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 15 |
| 6 | 45 |
| 7 | 144 |
| 8 | 512 |
| 9 | 1841 |
| 10 | 6579 |
| 11 | 23808 |
| 12 | 87380 |
| 13 | 322875 |
| 14 | 1198665 |
| 15 | 4473647 |
| 16 | 16777216 |
| 17 | 63164175 |
| 18 | 238612920 |
| 19 | 904200192 |
| 20 | 3435973836 |
| 21 | 13089461538 |
| 22 | 49977848925 |
| 23 | 191219367936 |
| 24 | 733007751680 |
| 25 | 2814750270420 |
| 26 | 10825961287995 |
| 27 | 41699995927744 |
| 28 | 160842843834660 |
| 29 | 621186162441675 |