bryce's at 189
 Code:
Function A($)	
	$a = $^0
	dim $i, $x, $b[$a-1],$s

;		for $i = $a-1 to 0 step -1 too long. fixing.
		for $i = -$a to -1
			$x = substr($,-$i,1)
			$b[~$i] = $s*((4<$x)+$x)+$x
			$s=$s^1
		next

		$i = execute("$X="+join($b,'+'))
		$a = ($>3 & $<7 & $a=16-($<4) & $x mod 10=)*left($,1)
Endfunction
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