text: Pell Number | Iterative Pell Number Series in Java ; calculate nth pell number ; driver function
code: class PellNumber { public static int pell ( int n ) { if ( n <= 2 ) return n ; int a = 1 ; int b = 2 ; int c ; for ( int i = 3 ; i <= n ; i ++ ) { c = 2 * b + a ; a = b ; b = c ; } return b ; } public static void main ( String args [ ] ) { int n = 4 ; System . out . println ( pell ( n ) ) ; } }