OFFSET
1,3
EXAMPLE
a(3) = 12 =
| 1 2 4|
| 7 8 11|
|13 14 16|.
a(4) = 0 because of the singular matrix 0 =
| 1 2 4 7|
| 8 11 13 14|
|16 19 21 22|
|25 26 28 31|.
a(6) = 0 because of the singular matrix whose lower right entry is 127.
MATHEMATICA
nn=10000; With[{xa=Select[Range[nn], OddQ[DigitCount[#, 2, 1]]&]}, Table[Det[ Partition[Take[xa, n^2], n]], {n, Floor[Sqrt[Length[xa]]]}]] (* Harvey P. Dale, Jun 28 2012 *)
PROG
(PARI) a(n)=matdet(matrix(n, n, i, j, k=(i-1)*n+j; 2*k-1-hammingweight(k-1)%2)) \\ Charles R Greathouse IV, Mar 29 2013
CROSSREFS
KEYWORD
sign
AUTHOR
Jonathan Vos Post, May 27 2006
EXTENSIONS
More terms from Harvey P. Dale, Jun 28 2012
STATUS
approved