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 | 15 |
| 1 | 54 |
| 2 | 141 |
| 3 | 324 |
| 4 | 699 |
| 5 | 1458 |
| 6 | 2985 |
| 7 | 6048 |
| 8 | 12183 |
| 9 | 24462 |
| 10 | 49029 |
| 11 | 98172 |
| 12 | 196467 |
| 13 | 393066 |
| 14 | 786273 |
| 15 | 1572696 |
| 16 | 3145551 |
| 17 | 6291270 |
| 18 | 12582717 |
| 19 | 25165620 |
| 20 | 50331435 |
| 21 | 100663074 |
| 22 | 201326361 |
| 23 | 402652944 |
| 24 | 805306119 |
| 25 | 1610612478 |
| 26 | 3221225205 |
| 27 | 6442450668 |
| 28 | 12884901603 |
| 29 | 25769803482 |