10 lines
157 B
Python
10 lines
157 B
Python
N = int(input())
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sigma = lambda k : int(0.5*k*(k+1))
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ans = 0
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for n in range(1,N+1) :
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if n==1 : ans = 3
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else : ans += sigma(n) + n*(n+1)
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print(ans) |