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 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 15 |
| 5 | 30 |
| 6 | 60 |
| 7 | 120 |
| 8 | 240 |
| 9 | 481 |
| 10 | 963 |
| 11 | 1927 |
| 12 | 3855 |
| 13 | 7710 |
| 14 | 15420 |
| 15 | 30840 |
| 16 | 61680 |
| 17 | 123361 |
| 18 | 246723 |
| 19 | 493447 |
| 20 | 986895 |
| 21 | 1973790 |
| 22 | 3947580 |
| 23 | 7895160 |
| 24 | 15790320 |
| 25 | 31580641 |
| 26 | 63161283 |
| 27 | 126322567 |
| 28 | 252645135 |
| 29 | 505290270 |
| 30 | 1010580540 |