数列｛an｝是正项等差数列,若bn=a1+a2+a3+……+an/n则数列｛bn｝也为等差数列,类比上述结论,写出正项等比数列｛cn｝,若dn=________,则数列｛dn｝也为等比数列

数列｛an｝是正项等差数列,若bn=a1+a2+a3+……+an/n则数列｛bn｝也为等差数列,类比上述结论,写出正项等比数列｛cn｝,若dn=________,则数列｛dn｝也为等比数列
数列｛an｝是正项等差数列,若bn=a1+a2+a3+……+an/n
则数列｛bn｝也为等差数列,类比上述结论,写出正项等比数列｛cn｝,若dn=________,则数列｛dn｝也为等比数列

数列｛an｝是正项等差数列,若bn=a1+a2+a3+……+an/n则数列｛bn｝也为等差数列,类比上述结论,写出正项等比数列｛cn｝,若dn=________,则数列｛dn｝也为等比数列
(c1*c2*c3*...*cn)根号n