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 | 3 |
| 3 | 9 |
| 4 | 31 |
| 5 | 117 |
| 6 | 459 |
| 7 | 1835 |
| 8 | 7449 |
| 9 | 30711 |
| 10 | 128601 |
| 11 | 546537 |
| 12 | 2354139 |
| 13 | 10260492 |
| 14 | 45173868 |
| 15 | 200578692 |
| 16 | 896865572 |
| 17 | 4033380894 |
| 18 | 18224524458 |
| 19 | 82664886074 |
| 20 | 376161628302 |
| 21 | 1716301466139 |
| 22 | 7848924260901 |
| 23 | 35966629306221 |
| 24 | 165109474283847 |
| 25 | 759210907786198 |
| 26 | 3496438156668822 |
| 27 | 16126158739138860 |