fork download 
  1. #include <stdio.h>
  2. // a{n} = 2a{n-1} + a{n-2}, a{1}=2, a{2}=3
  3.  
  4. int main(void) {
  5.     int n = 4;
  6.     int a1 = 2, a2 = 3, a3;
  7.  
  8.     for (int i = 3; i <= n; i++) {
  9.         a3 = 2 * a2 + a1; 
  10.         a1 = a2; 
  11.         a2 = a3;
  12.     }
  13.  
  14.     printf("数列a%dの値は%d\n", n, a3);
  15.     return 0;
  16. }
  17.  
Success #stdin #stdout 0.01s 5316KB
comments (?)
stdin 
Standard input is empty
stdout 
数列a4の値は19
https://ideone.com/2GOg09
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!