document.write( "Question 1058638: What's the next number in the series?
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Algebra.Com's Answer #673744 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "The answer is 8.  I'll explain why.\r\n" );
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document.write( "4, 12, 13, 15, 14, 10, 11, 9 ...\r\n" );
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document.write( "This is a subsequence of the sequence of binary gray codes \r\n" );
document.write( "converted to base ten.  The sequence of gray codes \r\n" );
document.write( "beginning with 0 converted to base 10 is:\r\n" );
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document.write( "0,1,3,2,6,7,5,4,12,13,15,14,10,11,9,8,24,25,27,26,30,31,29,...\r\n" );
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document.write( "The binary gray codes are below.  Each is considered as having \r\n" );
document.write( "an arbitrary number of 0's in front:\r\n" );
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document.write( "0...00000 which converted to base 10 is 0\r\n" );
document.write( "0...00001 which converted to base 10 is 1\r\n" );
document.write( "0...00011 which converted to base 10 is 3\r\n" );
document.write( "0...00010 which converted to base 10 is 2\r\n" );
document.write( "0...00110 which converted to base 10 is 6\r\n" );
document.write( "0...00111 which converted to base 10 is 7\r\n" );
document.write( "0...00101 which converted to base 10 is 5\r\n" );
document.write( "0...00100 which converted to base 10 is 4 <-- your sequence starts here.\r\n" );
document.write( "0...01100 which converted to base 10 is 12\r\n" );
document.write( "0...01101 which converted to base 10 is 13\r\n" );
document.write( "0...01111 which converted to base 10 is 15\r\n" );
document.write( "0...01110 which converted to base 10 is 14\r\n" );
document.write( "0...01010 which converted to base 10 is 10\r\n" );
document.write( "0...01011 which converted to base 10 is 11\r\n" );
document.write( "0...01001 which converted to base 10 is 9\r\n" );
document.write( "0...01000 which converted to base 10 is 8 <-- the next one after the 9.\r\n" );
document.write( "0...11000 which converted to base 10 is 24\r\n" );
document.write( "0...11001 which converted to base 10 is 25\r\n" );
document.write( "0...11010 which converted to base 10 is 27\r\n" );
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document.write( "Rule for obtaining any gray code from the\r\n" );
document.write( "preceding gray code:\r\n" );
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document.write( "Change the digit which is farthest to the right \r\n" );
document.write( "WHICH DOES NOT GIVE A PREVIOUS GRAY CODE, from\r\n" );
document.write( "a 0 to a 1, or from a 1 to a 0. \r\n" );
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document.write( "Edwin
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