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 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 24 |
| 5 | 72 |
| 6 | 186 |
| 7 | 438 |
| 8 | 990 |
| 9 | 2142 |
| 10 | 4560 |
| 11 | 9492 |
| 12 | 19620 |
| 13 | 40068 |
| 14 | 81534 |
| 15 | 164892 |
| 16 | 332808 |
| 17 | 669528 |
| 18 | 1345554 |
| 19 | 2699448 |
| 20 | 5412636 |
| 21 | 10843038 |
| 22 | 21714972 |
| 23 | 43467342 |
| 24 | 86995428 |
| 25 | 174069306 |
| 26 | 348265164 |
| 27 | 696694692 |
| 28 | 1393652298 |
| 29 | 2787646380 |
| 30 | 5575837836 |
| 31 | 11152384044 |
| 32 | 22305891948 |
| 33 | 44613248352 |
| 34 | 89228806704 |
| 35 | 178460625402 |
| 36 | 356925987924 |