RPS #006 - Not so expert series problem

Algebra Level 3

Let $T_{n}$ denotes the $n^{th}$ term in triangle number series $(1,3,6,10,...)$ for every positive integers $n$

Consider two function of $S_{n} = T_1 + T_2 + T_3 + ... + T_n$ and $R_n = S_1 + S_2 + S_3 + ... + S_n$

Find the value of $R_{21}$

(You can see more of my problem series in my profile)

2 solutions

A Steven Kusuman
Jan 26, 2015

using namespace std;

int main(){

long long tit rimba[100],norman[75],step[30]={0},xx=0;

for (int i=1;i<100;i++){

xx=xx+i;

rimba[i]=xx;

}

xx=0;

for (int i=1;i<75;i++){

    xx=xx+rimba[i];

norman[i]=xx;

}

xx=0;

for (int i=1;i<30;i++){

xx=xx+norman[i];

step[i]=xx;

} printf("%lld",step[21]); }

Aditya Putra Santosa
Jan 27, 2015

var

a,result, b: integer;

d : integer;

begin

a := 1;

b := 21;

for d := 1 to 21 do begin

    result := result + (b*a) ;

    b := b-1;

    a := a+d+1;

end;

writeln(result) ;

end.