<?php
	function CabecalhoPlanilha( $numero ) {
		$string = '';
		while( $numero ) {
			$string = chr( 65 + ( --$numero % 26 ) ) . $string;
			$numero = (int) ( $numero / 26 );
		}
		return $string;
	}
	
	echo CabecalhoPlanilha( 26 ) . "\n";
	echo CabecalhoPlanilha( 27 ) . "\n";
	echo CabecalhoPlanilha( 1024 ) . "\n";
?>