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 | 3 |
| 2 | 12 |
| 3 | 55 |
| 4 | 272 |
| 5 | 1413 |
| 6 | 7599 |
| 7 | 41933 |
| 8 | 236053 |
| 9 | 1350093 |
| 10 | 7822620 |
| 11 | 45817390 |
| 12 | 270815730 |
| 13 | 1613300978 |
| 14 | 9676131942 |
| 15 | 58380176644 |
| 16 | 354081959367 |
| 17 | 2157570900137 |
| 18 | 13201923181308 |
| 19 | 81084900544971 |
| 20 | 499711105642851 |
| 21 | 3089163236655363 |
| 22 | 19150916212748940 |
| 23 | 119031956868317285 |