OFFSET
1,1
COMMENTS
This is called "square" because the Gaussian integers involved here form a square on the complex plane.
All terms are purely real integers, but a(6) has more than a hundred digits.
EXAMPLE
a(1) = 1 * (1 + i) * i * (-1 + i) * -1 * (-1 - i) * -i * (1 - i) = -4.
MATHEMATICA
Table[Times@@ReplaceAll[Flatten[Table[a + b I, {a, -n, n}, {b, -n, n}]], 0 -> 1], {n, 10}]
CROSSREFS
KEYWORD
sign
AUTHOR
Alonso del Arte, Jan 09 2012
STATUS
approved