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 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 7 |
| 5 | 18 |
| 6 | 45 |
| 7 | 110 |
| 8 | 267 |
| 9 | 652 |
| 10 | 1602 |
| 11 | 3960 |
| 12 | 9845 |
| 13 | 24594 |
| 14 | 61689 |
| 15 | 155270 |
| 16 | 391962 |
| 17 | 991968 |
| 18 | 2515964 |
| 19 | 6393610 |
| 20 | 16275174 |
| 21 | 41491776 |
| 22 | 105922244 |
| 23 | 270734244 |
| 24 | 692756227 |
| 25 | 1774418286 |
| 26 | 4549173861 |
| 27 | 11672860634 |
| 28 | 29975156134 |
| 29 | 77029918152 |
| 30 | 198083586300 |
| 31 | 509692521982 |