The length of the second circle is 2+3+4+4+2= 15.
The length of the third lap is: 3+5+6+6+3=23.
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The length of the nth circle is n+(2n-1)+2n+2n+n = 8n-1.
Therefore, when n= 10, the length of 10 cycle is 79.
So the answer is: 79.