Question 1181767


{{{sum( 2*3^(n - 1),n=1,12)=531440}}}


check by finding all terms:


{{{t[1]= 2(3) ^(1-1)=2}}}
{{{t[2]= 2(3) ^(2-1)=2*3^1=6}}}
{{{t[3]= 2(3) ^(3-1)=2*3^2=18}}}
{{{t[4]= 2(3) ^(4-1)=2*3^3=54}}}
{{{t[5]= 2(3) ^(5-1)=2*3^4=162}}}
{{{t[6]= 2(3) ^(6-1)=2*3^5=486}}}
{{{t[7]= 2(3) ^(7-1)=2*3^6=1458}}}
{{{t[8]= 2(3) ^(8-1)=2*3^7=4374}}}
{{{t[9]= 2(3) ^(9-1)=2*3^8=13122}}}
{{{t[10]= 2(3) ^(10-1)=2*3^9=39366}}}
{{{t[11]= 2(3) ^(11-1)=2*3^10=118098}}}
{{{t[12]= 2(3) ^(12-1)=2*3^11=354294}}}

sum:

{{{2+6+18+54+162+486+1458+4374+13122+39366+118098+354294=531440}}}

{{{531440=531440}}}