Las siguientes funciones complementarias obtienen el numero de columna en Excel basado en el nombre y viceversa.
Ej 
GetExcelColumnName(731) ==> "ABC"
GetExcelColumnNumber("AB") ==> 28
/// <summary>
        /// Get the a Excel Column based on a column number
        /// </summary>
        /// <param name="ColumnNumber">Column Number</param>
        /// <returns></returns>
        public static string GetExcelColumnName(int ColumnNumber)
        {
            int intDividend = ColumnNumber;
            string strColumnName = String.Empty;
            int intModulo;
            while (intDividend > 0)
            {
                intModulo = (intDividend - 1) % 26;
                strColumnName = Convert.ToChar(65 + intModulo).ToString() + strColumnName;
                intDividend = (int)((intDividend - intModulo) / 26);
            }
            return strColumnName;
        }
        /// <summary>
        /// Get the Excel column number based on a excel column name
        /// </summary>
        /// <param name="ColumnName">Nombre de la columna</param>
        /// <returns></returns>
        public static int GetExcelColumnNumber(string  ColumnName)
        {
            int columnNumber=0;
            for (int i=0;i<ColumnName.Length ;i++){
                columnNumber = 
                    columnNumber * 26 +(Convert.ToInt32  (ColumnName [i]) - 64) 
                    ;
            }
            return columnNumber;
        }
