recursion - Coding a recurrence relation in Java -

i writing code calculates recursive mathematical problem, called foo.

the condition should be,
if n < 4: foo(n) = n
if n >= 4: foo(n) = n + foo(n - 1) + 2*foo(n-2).

public class foo {      public static int foo(n) {         if(n < 4) {             return n;         } else if(n >= 4) {          }     }       public static void main(string[] args) {      }    } 

i stuck here... final purpose state values of foo(1), foo(2), foo(3), foo(4), foo(5), foo(6), foo(7).

also, allowed put main method in foo class?

the following function 1 you're looking for:

public static int bar(int n){     if(n < 4){         return n;     }      return n + bar(n - 1) + 2*bar(n-2); } 

first of all, if want function call main directly, must static, because you're not allowed call non-static method static context.

static functions (methods) called on classes, not on objects. therefor, there no need create object - execute foo.bar(anyint).

then, need check if n smaller 4 - if is, return n.

there no need else clause, because if returned inside if, won't execute more code function, return means exit function now.

then, please follow java naming strategies, start class name capital letter (foo instead of foo). foo perfect name field, variable or method, not class.

the code should in end like:

public class foo {      public static int bar(int n){         if(n < 4){             return n;         }          return n + bar(n - 1) + 2*bar(n-2);     }      public static void main(string[] args) {          (int = 1; < 8; i++) {             system.out.println("bar(" + + ") " + foo.bar(i));         }     }    } 

the output be:

>bar(1) 1 >bar(2) 2 >bar(3) 3 >bar(4) 11 >bar(5) 22 >bar(6) 50 >bar(7) 101