Perhaps someone should forward this upstream. $\sum_{ n > 0} \pi^n$ certainly diverges though mpmath claims it equals -pi/(pi-1)
sage: import mpmath sage: mpmath.mp.pretty=True;mpmath.mp.dps=40 sage: r1=mpmath.nsum(lambda n: mpmath.pi**n,[ 1, mpmath.inf]) sage: r1 -1.466942206924259859983394813233667573143 sage: sage: r2=-mpmath.pi/(mpmath.pi - 1) sage: r1-r2 0.0 sage: r3=mpmath.nsum(lambda n: mpmath.mpf('2')**n,[ 1, mpmath.inf]);r3 -2.0 Computing zeta(2) appears OK: sage: z2=mpmath.nsum(lambda n: 1/n**2,[ 1, mpmath.inf]);z2 1.644934066848226436472415166646025189219 sage: z2 - mpmath.zeta(2) 0.0 -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.