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 | 41 |
| 4 | 140 |
| 5 | 457 |
| 6 | 1485 |
| 7 | 4732 |
| 8 | 14986 |
| 9 | 47025 |
| 10 | 146784 |
| 11 | 455683 |
| 12 | 1409122 |
| 13 | 4341456 |
| 14 | 13336440 |
| 15 | 40858875 |
| 16 | 124894889 |
| 17 | 380993722 |
| 18 | 1160145321 |
| 19 | 3527008680 |
| 20 | 10707133507 |
| 21 | 32461710583 |
| 22 | 98300107420 |
| 23 | 297348593017 |
| 24 | 898559807247 |
| 25 | 2712889137261 |
| 26 | 8183743165156 |
| 27 | 24668014337837 |