ecuació diferencial

x·d_{xx}^{2}[y(x)]+d_{x}[y(x)] = y(x)

y(x) = ∑ ( ( 1/(n^{2})! )·x^{n} ) = ∑ ( x^{i(n)} )

p+1 = n <==> ∑ ( x^{i(n+(-1))} ) = ∑ ( x^{i(p)} )

x·d_{xx}^{2}[y(x)]+d_{x}[y(x)] = ∑ ( c_{n}·x^{n} )

y(x) = ∑ ( c_{(n+(-1))}·( 1/(n^{2}) )·x^{n} )