progressions aritmética, geométrica y potencial

( a_{1}=b & a_{n+1} = a_{n}+b ) <==> a_{n+1}=(n+1)·b


( a_{1}=b & a_{n+1} = b·a_{n} ) <==> a_{n+1}=b^{(n+1)}


( a_{1}=b & a_{n+1} = (a_{n})^{m} ) <==> a_{n+1}=b^{m^{n+1}}