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 | 3 |
| 2 | 11 |
| 3 | 51 |
| 4 | 227 |
| 5 | 963 |
| 6 | 3971 |
| 7 | 16131 |
| 8 | 65027 |
| 9 | 261123 |
| 10 | 1046531 |
| 11 | 4190211 |
| 12 | 16769027 |
| 13 | 67092483 |
| 14 | 268402691 |
| 15 | 1073676291 |
| 16 | 4294836227 |
| 17 | 17179607043 |
| 18 | 68718952451 |
| 19 | 274876858371 |
| 20 | 1099509530627 |
| 21 | 4398042316803 |
| 22 | 17592177655811 |
| 23 | 70368727400451 |
| 24 | 281474943156227 |
| 25 | 1125899839733763 |