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 | -2 |
| 1 | -1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 13 |
| 5 | 29 |
| 6 | 61 |
| 7 | 125 |
| 8 | 253 |
| 9 | 509 |
| 10 | 1021 |
| 11 | 2045 |
| 12 | 4093 |
| 13 | 8189 |
| 14 | 16381 |
| 15 | 32765 |
| 16 | 65533 |
| 17 | 131069 |
| 18 | 262141 |
| 19 | 524285 |
| 20 | 1048573 |
| 21 | 2097149 |
| 22 | 4194301 |
| 23 | 8388605 |
| 24 | 16777213 |
| 25 | 33554429 |
| 26 | 67108861 |
| 27 | 134217725 |
| 28 | 268435453 |
| 29 | 536870909 |
| 30 | 1073741821 |
| 31 | 2147483645 |