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 | 23 |
| 2 | 109 |
| 3 | 407 |
| 4 | 1777 |
| 5 | 7813 |
| 6 | 35245 |
| 7 | 160953 |
| 8 | 742857 |
| 9 | 3455597 |
| 10 | 16177459 |
| 11 | 76129593 |
| 12 | 359815609 |
| 13 | 1706868797 |
| 14 | 8122449787 |
| 15 | 38757778297 |
| 16 | 185382123417 |
| 17 | 888570946797 |
| 18 | 4267072020187 |
| 19 | 20525592779337 |
| 20 | 98881792935527 |
| 21 | 477011872851207 |