Find the n , k term of matrix of Gilbreath 's conjecture
static int Gilbreath ( HashMap < Integer , HashMap < Integer , Integer > > mp , HashMap < Integer , HashMap < Integer , Integer > > hash , int n , int k ) { if ( hash . containsKey ( n ) && hash . get ( n ) . containsKey ( k ) && hash . get ( n ) . get ( k ) != 0 ) return mp . get ( n ) . get ( k ) ;