### Computing Ramanujan's tau function

Our program is simple-minded and uses the formula

when n is prime and the formula

Here σ_{k}(n) is the sum of the k-th powers of the divisors of n.

(See T.M. Apostol, *Modular functions and Dirichlet series in number theory*, 20-22, 140 and the MathWorld account.)

*Last modified 16th August 2006*

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