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 | 56 |
| 2 | 228 |
| 3 | 932 |
| 4 | 3736 |
| 5 | 15512 |
| 6 | 62040 |
| 7 | 242264 |
| 8 | 969136 |
| 9 | 3985840 |
| 10 | 15943080 |
| 11 | 62096808 |
| 12 | 248388496 |
| 13 | 1021909904 |
| 14 | 4087635248 |
| 15 | 15883066672 |
| 16 | 63532285248 |
| 17 | 261545377088 |
| 18 | 1046181434696 |
| 19 | 4065904153928 |
| 20 | 16263616920064 |
| 21 | 66960253254144 |