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Superperfect Number in C programming
The concept of super perfect number is similar to the perfect number. It was found by D Suryanarayana in 1969. He generalized the super perfect number as a number that satisfies the following formula :
sig(sig(n)) = 2n
Here, sig(n) is the function that calculates the sum of divisors of a number, it is also known as divisor summatory function.
The following example with making this concept clear to you :
we need to check if the number N is a superperfect number or not:
N = 16
Output
yes
Explanation − to check whether a number is a perfect number or not we will find the sum of its divisors.
sig(16) = 1 + 2 + 4 + 8 + 16 = 31 ( divisors of 16 are 1, 2, 4, 8, 16 1, 2, 4, 8, 16) sig( 31) = 1 + 31 = 32( 31 is a prime number) 2*n = 32 = sig(sig(n))
This shows that 16 is a superperfect number.
Now let's see an example of a number which is not a superperfect number.
n = 6 sig(6) = 1 + 2 + 3 + 6= 12 sig(12) = 1 + 2 + 3 + 4 +6 + 12 = 28 6*2 = 12 != 28.
This shows that 6 is not a super perfect number
Example
#include<stdio.h>
//function to find the sum of divisors of num
int divisorsum(int n){
int sum = 0; // intialising the sum
for (int i=1; i*i <= n; ++i){
if (n%i == 0) { // find the sum of divisors
if (i == (n/i))
sum += i;
else
sum += (i + n/i);
}
}
return sum;
}
int main() {
int n = 16;
int n1 = divisorsum(n);
if(2*n == divisorsum(n1)){
printf("The number %d is a superperfect number", n);
} else{
printf("The number %d is not a superperfect number", n);
}
return 0;
}Output
The number 16 is a super perfect number
Updated on: 13-Aug-2019
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