ecuació diferencial

d_{xx}^{2}[y(x)] = (1/x)·y(x)

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

x·d_{xx}^{2}[ ∑ ( (1/n)·(1/(n+1)) )!·x^{(n+1)} ] = ∑ ( (1/(n+(-1)))·(1/n) )!·x^{n}

n=p+1

y(x) = ∑ ( (1/p)·(1/(p+1)) )!·x^{(p+1)}