public static int kthgroupsum ( int k ) {
  int cur = ( k * ( k - 1 ) ) + 1 ;
  int sum = 0 ;
  while ( k -- > 0 ) {
    sum += cur ;
    cur += 2 ;
  }
  return sum ;
}

public static int kthgroupsum ( int k ) { int cur = ( k * ( k - 1 ) ) + 1 ; int sum = 0 ; while ( k -- > 0 ) { sum += cur ; cur += 2 ; } return sum ; }
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