(a+a+b(n-1)) = ((n(a+a+b(n-1))) 
2)2+((n(a+a+b(n-1))) rem 2)
((n(a+a+b(n-1))) rem 2) = 0
i | i < n)2 = n(a+a+b(n-1))
2sum(a+bi | i < n) = 2((n(a+a+b(n-1))) 2)
a:, n:
. a = (a n)n+(a rem n)
[n(a+a+b(n-1));2]
(a+a+b(n-1))) rem 2) = 0)
| 1 | 5. n(a+a+b(n-1)) = ((n(a+a+b(n-1))) 2)2+((n(a+a+b(n-1))) rem 2) ((n(a+a+b(n-1))) rem 2) = 0 | 5 steps |
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