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 | 5 |
| 3 | 13 |
| 4 | 31 |
| 5 | 75 |
| 6 | 181 |
| 7 | 437 |
| 8 | 1055 |
| 9 | 2547 |
| 10 | 6149 |
| 11 | 14845 |
| 12 | 35839 |
| 13 | 86523 |
| 14 | 208885 |
| 15 | 504293 |
| 16 | 1217471 |
| 17 | 2939235 |
| 18 | 7095941 |
| 19 | 17131117 |
| 20 | 41358175 |
| 21 | 99847467 |
| 22 | 241053109 |
| 23 | 581953685 |
| 24 | 1404960479 |
| 25 | 3391874643 |
| 26 | 8188709765 |
| 27 | 19769294173 |
| 28 | 47727298111 |
| 29 | 115223890395 |
| 30 | 278175078901 |
| 31 | 671574048197 |