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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 19 |
| 5 | 55 |
| 6 | 159 |
| 7 | 471 |
| 8 | 1403 |
| 9 | 4191 |
| 10 | 12551 |
| 11 | 37615 |
| 12 | 112787 |
| 13 | 338279 |
| 14 | 1014703 |
| 15 | 3043911 |
| 16 | 9131435 |
| 17 | 27393839 |
| 18 | 82180823 |
| 19 | 246541407 |
| 20 | 739622595 |
| 21 | 2218865335 |
| 22 | 6656592255 |
| 23 | 19969771063 |
| 24 | 59909304539 |
| 25 | 179727900415 |
| 26 | 539183681191 |
| 27 | 1617551013071 |
| 28 | 4852652992755 |
| 29 | 14557958907655 |
| 30 | 43673876615503 |