The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | 0 |
| 6 | 4 |
| 7 | 10 |
| 8 | 33 |
| 9 | 93 |
| 10 | 264 |
| 11 | 729 |
| 12 | 1999 |
| 13 | 5437 |
| 14 | 14726 |
| 15 | 39757 |
| 16 | 107118 |
| 17 | 288201 |
| 18 | 774672 |
| 19 | 2080936 |
| 20 | 5587388 |
| 21 | 14997840 |
| 22 | 40249449 |
| 23 | 108001720 |
| 24 | 289774494 |
| 25 | 777430359 |
| 26 | 2085660586 |
| 27 | 5595162045 |
| 28 | 15009725921 |
| 29 | 40264911876 |
| 30 | 108013136968 |
| 31 | 289750079191 |
| 32 | 777264097335 |
| 33 | 2085030095791 |
[1,-1,1,-1,1,0,4,10,33,93,264,729,1999,5437,14726, 39757,107118,288201,774672,2080936,5587388, 14997840,40249449,108001720,289774494,777430359, 2085660586,5595162045,15009725921,40264911876, 108013136968,289750079191,777264097335, 2085030095791] |