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 | 4 |
| 2 | 15 |
| 3 | 53 |
| 4 | 185 |
| 5 | 643 |
| 6 | 2234 |
| 7 | 7764 |
| 8 | 26988 |
| 9 | 93819 |
| 10 | 326149 |
| 11 | 1133811 |
| 12 | 3941521 |
| 13 | 13702079 |
| 14 | 47633109 |
| 15 | 165588965 |
| 16 | 575643853 |
| 17 | 2001134880 |
| 18 | 6956629199 |
| 19 | 24183622175 |
| 20 | 84070541130 |
| 21 | 292257951771 |
| 22 | 1015988587832 |
| 23 | 3531923782817 |
| 24 | 12278174929397 |
| 25 | 42683134990390 |