text: Pell Number | Pell Number Series using Recursion in JAVA ; calculate n - th Pell number ; driver function
code: class PellNumber { public static int pell ( int n ) { if ( n <= 2 ) return n ; return 2 * pell ( n - 1 ) + pell ( n - 2 ) ; } public static void main ( String args [ ] ) { int n = 4 ; System . out . println ( pell ( n ) ) ; } }