A sequence of positive real numbers a_1, a_2, a_3... has the property that for i>=2, each a_i is equal to the sum of all the previous terms. If a_19=91, then what is a_20?

Guest Feb 16, 2021

#2**+1 **

The summation for n = 19 is usually 190

this sequence is only 91

190x =91

x = 91/190 so the numbers in the sequence are reduced by this multiplier

\( \sum_{1}^{20} ( 91/190) n = 100.578947368\) This would be a_{20}

ElectricPavlov Feb 16, 2021