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 | 2 |
| 4 | 10 |
| 5 | 20 |
| 6 | 52 |
| 7 | 112 |
| 8 | 234 |
| 9 | 484 |
| 10 | 992 |
| 11 | 2018 |
| 12 | 4060 |
| 13 | 8140 |
| 14 | 16336 |
| 15 | 32706 |
| 16 | 65474 |
| 17 | 131004 |
| 18 | 262056 |
| 19 | 524184 |
| 20 | 1048460 |
| 21 | 2097044 |
| 22 | 4194176 |
| 23 | 8388480 |
| 24 | 16777084 |
| 25 | 33554264 |
| 26 | 67108704 |
| 27 | 134217560 |
| 28 | 268435256 |
| 29 | 536870708 |
| 30 | 1073741584 |
| 31 | 2147483416 |
| 32 | 4294967054 |
| 33 | 8589934308 |
| 34 | 17179868884 |
| 35 | 34359738044 |
| 36 | 68719476404 |
| 37 | 137438953124 |
| 38 | 274877906592 |
| 39 | 549755813536 |