recursion - Sequence 1, 3, 8, 18, 38, 78 from a recursive function -

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i'm trying write recursive function in java display n element in mathematical number sequence (1 3 8 18 38 78).

this i've managed far:

public static int recfunc(int i) {     if(i==1) { return 1; }     if(i==2) { return 2+recfunc(i-1); }     if(i==3) { return 5+recfunc(i-1); }     if(i>3) { return ((2^(i-3))*5)+recfunc(3); }     return 0; }

to calculate n(>3), add 2^(i-3) each step(i>3) , add 8 in end. so, 6th element, have calculation: 40 + 20 + 10 + 8 = 78.

the problem above code calculates increase in number between 2 n(s) , ads 5 + 2 + 1 (8) it, doesn't apply previous steps (20 + 10).

update:

i'm getting somewhere, still doesn't should.

public static int recfunc(int i, boolean param) {     if(param==false) {         if(i==1) { return 1; }         if(i==2) { return 2+recfunc(i-1, false); }         if(i==3) { return 5+recfunc(i-1, false); }         if(i>3) { param = true; }     }     if(param==true) {         if(i==4) {             return ((2^(i-3))*5)+recfunc(i-1, false); }         else {             return ((2^(i-3))*5)+recfunc(i-1, true); }     }     return 0; }

the problem power function. ^ in java not mean raise power. means xor.

you can use java's math.pow()

int recfunc(int i) {     if(i==1) { return 1; }     if(i==2) { return 2+recfunc(i-1); }     if(i==3) { return 5+recfunc(i-1); }     if(i>3) {         return ((math.pow(2,(i-3))*5)+recfunc(i-1));  }     return 0; }

hope helps.


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