User blog comment:Wythagoras/FGH Dollars Function/@comment-10429372-20130710181242/@comment-10429372-20130711054937

well, [0,0,0,1] ~ phi(2,0,0)

[0,0,0,2] ~ phi(3,0,0)

[0,0,0,[0,0,0,1]] ~ phi(phi(2,0,0),0,0)

[0,0,0,[0,0,0,1]_2] ~ phi(1,0,0,0)

each next subscript leads to the next variable in phi.