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 | 0 |
| 2 | 9 |
| 3 | 54 |
| 4 | 243 |
| 5 | 1008 |
| 6 | 4077 |
| 7 | 16362 |
| 8 | 65511 |
| 9 | 262116 |
| 10 | 1048545 |
| 11 | 4194270 |
| 12 | 16777179 |
| 13 | 67108824 |
| 14 | 268435413 |
| 15 | 1073741778 |
| 16 | 4294967247 |
| 17 | 17179869132 |
| 18 | 68719476681 |
| 19 | 274877906886 |
| 20 | 1099511627715 |
| 21 | 4398046511040 |
| 22 | 17592186044349 |
| 23 | 70368744177594 |
| 24 | 281474976710583 |
| 25 | 1125899906842548 |