Create A Function And Call It In Anonymous Block

I made this script but I still don't quite understand if the syntax is correct. I just wanted to create a function and call it in an anonymous block. I then wanted it to use a variable as a parameter in an iteration and output the variable every iteration. It's done basically but I know it's not 100% right. The fibonacci function looks like its going to loop an infinite number of times if the parameter is greater than 2.

CREATE OR REPLACE PACKAGE myPACKAGE AS
CREATE OR REPLACE FUNCTION fibonacci
(n BINARY_DOUBLE) RETURN BINARY_DOUBLE IS
BEGIN
IF n <= 2 THEN
RETURN 1;
[code]........