Pulling in Nearby Entities to a Block; Faster the Closer to the Block

I'm trying to make a black hole block move entities nearby toward the block using this: (Attempt to override motion vector of [Entity iterator] to vx: [{blockx}-{x position of entity}/{change}] vy: [{blocky-y position}/{change}] vz: [{blockz-z position}/{change}]), (See image). Change is my variable and it makes it slower. The only problem with it is that it pulls entities realy fast the further away from the black hole they are. I'm wanting to make them get pulled more the closer they are, similar to an actual black hole. Is anyone able to change my original equation to fit that?