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sign = 1
pi_4 = 0
for k in range(0,8) :
    pi_4 += sign / (2*k+1)
    print(pi_4, sign/(2*k+1), sign)
    sign = sign * (-1)
print(pi_4*4)

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2:

print(4*sum(map(lambda k: (1+(k%2)*(-2))/(2*k+1), range(0,8))))