25spheres.txt

N:=100;

A:=NullMat(N,N);;
A:=List([1..N],i->StructuralCopy(A));;
A[Int(N/2)][Int(N/2)][Int(N/2)]:=1;

M:=PureCubicalComplex(A*0);;
B2:=PureCubicalComplex(A);

for i in [1..Int(N/2)-1] do
B1:=B2;
B2:=ThickenedPureComplex(B1);
S:=PureComplexDifference(B2,B1);
if IsOddInt(i) then
M:=PureComplexUnion(M,S);
fi;
od;

for i in [2..Int(N/2)-1] do
M!.binaryArray[Int(N/2)][Int(N/2)][i]:=1;
od;