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 | 3 |
| 2 | 15 |
| 3 | 61 |
| 4 | 250 |
| 5 | 966 |
| 6 | 3691 |
| 7 | 13708 |
| 8 | 50198 |
| 9 | 180756 |
| 10 | 642883 |
| 11 | 2259194 |
| 12 | 7859454 |
| 13 | 27086808 |
| 14 | 92579267 |
| 15 | 314011481 |
| 16 | 1057679231 |
| 17 | 3539727315 |
| 18 | 11776328715 |
| 19 | 38963355007 |
| 20 | 128255099092 |
| 21 | 420155031109 |
| 22 | 1370225125574 |
| 23 | 4449779889260 |
| 24 | 14393128980829 |
| 25 | 46380744221539 |