On 06/15/10 21:49, superpollo wrote: > goal (from e.c.m.): evaluate > 1^2+2^2+3^2-4^2-5^2+6^2+7^2+8^2-9^2-10^2+...-2010^2, where each three > consecutive + must be followed by two - (^ meaning ** in this context) > > my solution: > >>>> s = 0 >>>> for i in range(1, 2011): > .... s += i**2 > .... if not (i+1)%5: > .... s -= 2*i**2 > .... if not i%5: > .... s -= 2*i**2 > .... >>>> print s > 536926141
Probably bending the rules a little bit: >>> sum(x**2 - 8*x - 20 for x in range(1, 2010, 5)) 536926141 another variation: >>> sum((x - 10) * (x + 2) for x in range(1, 2010, 5)) 536926141 -- http://mail.python.org/mailman/listinfo/python-list
