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 | 1 |
| 1 | 16 |
| 2 | 80 |
| 3 | 536 |
| 4 | 4128 |
| 5 | 32808 |
| 6 | 262192 |
| 7 | 2097208 |
| 8 | 16777280 |
| 9 | 134217800 |
| 10 | 1073741904 |
| 11 | 8589934680 |
| 12 | 68719476832 |
| 13 | 549755813992 |
| 14 | 4398046511216 |
| 15 | 35184372088952 |
| 16 | 281474976710784 |
| 17 | 2251799813685384 |
| 18 | 18014398509482128 |
| 19 | 144115188075856024 |
| 20 | 1152921504606847136 |
| 21 | 9223372036854775976 |