Is there a reference about determining the minimum radius of a circle that would cover n circles of radius 1 that are in a square packing configuration ( see Wolfram's MathWorld packing packing description)?
This is a different problem than the "best known packing of equal circles in a circle", though for n=1, 2, and 4 it would have the same result.
For a hexagonal packing configuration, n=1, 2, 3, 7, would have the same result as "best know packing of equal circles in a circle". Believe 6 also does, but would actually cover 7.