On 15 June 2010 21:49, superpollo <ute...@esempio.net> 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) >
Obligatory one-liner: >>> sum((1, 1, 1, -1, -1)[(x-1) % 5] * x**2 for x in xrange(1, 2011)) 536926141 Cheers, Xav
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