python求和

单数求和
def sumOne(n):
    sum=0
    for i in range(1,n+1):
        sum+=i
    return sum

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平方求和

def sumSqu(n):
    sum=0
    for i in range(1,n+1):
        sum+=i*i
    return sum

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立方求和

def sumCube(n):
    sum=0
    for i in range(1,n+1):
        sum+=i*i*i
    return sum

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