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 | 12 |
| 3 | 36 |
| 4 | 108 |
| 5 | 316 |
| 6 | 916 |
| 7 | 2628 |
| 8 | 7500 |
| 9 | 21268 |
| 10 | 60092 |
| 11 | 169092 |
| 12 | 474924 |
| 13 | 1329188 |
| 14 | 3715244 |
| 15 | 10359636 |
| 16 | 28856252 |
| 17 | 80220244 |
| 18 | 222847804 |
| 19 | 618083972 |
| 20 | 1713283628 |
| 21 | 4742946484 |
| 22 | 13123882524 |
| 23 | 36274940740 |
| 24 | 100226653420 |
| 25 | 276669062116 |
| 26 | 763482430316 |
| 27 | 2105208491748 |
| 28 | 5803285527724 |