In enunt s-a strecurat o greseala, cred ca
A=3^(2n+5)*7^n -63^(n+1) -3^(2n+1)*7^(n+2).
A=3^(2n+5)*7^n -9^(n+1)*7^(n+1) -3^(2n+1)*7^(n+2)
A=3^(2n+5)*7^n -3^(2n+2)*7^(n+1) -3^(2n+1)*7^(n+2)
A=3^(2n+1)*7^n *(3^4 -3*7 -7^2)=3*3^2n *7^n *(81-21-49)
A=3*3^2n *7^n *11=33*3^2n *7^n=m33, m=multiplu
A se divide cu 33
Daca sunt neclaritati le lamurim!
''*''=inmultit
''^''=la puterea