c - Working on a Fibonnaci/mysequence code -

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i working on code suppose calculate sequence:

           a(n+2)=-2(n+1)+3a(n)       a(0)=2     a(1)= -1

unfortunately cannot figure out. i'm new @ (about month) , i'm going try best on own, need help. thank whoever decides me.

#include <stdio.h>  int mysequence(int n) {    if (n==0) return 2;   if (n==1) return -1;   if (n==2) return 8;   return (2 * mysequence(n+1) + mysequence(n+2))/3; }  int main() {   int n;   printf("enter n = ");   scanf("%d", &n);   printf("%d\n",mysequence(n));   return 0; }

look @ line return (2 * mysequence(n+1) + mysequence(n+2))/3 , compare know sequence: a(n+2)=-2(n+1)+3a(n).

they have nothing in common.

what want return (-2*mysequence(n-1) + 3*mysequence(n-2)). why, coefficients should clear enough, copied definition. reason call next level of recursion n-1 , n-2 quite simple, observe:
a(n+2)=-2(n+1)+3a(n) -> substitute n n-2 -> a(n)=-2(n-1)+3a(n-2).


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