create a polygon sphere with 400 vertex, and then using particle tool to create 400 particles without space. Finally, you can add the following script into the particle position area (choose creation expression).
float $verticeX, $verticeY, $verticeZ;
$sel = `pointPosition -w pSphere1.vtx[particleShape1.particleId]`;
$verticeX = $sel[0];
$verticeY = $sel[1];
$verticeZ = $sel[2];
particleShape1.position = <<$verticeX, $verticeY, $verticeZ>>;