OFFSET
1,3
COMMENTS
n=p_1^a_1*...*p_r^a_r => tau(p_1^(p_1^a_1-1)*...*p_r^(p_r^a_r-1))=n, so sequence is well-defined.
FORMULA
a(p)=p^(p-2), a(pq)=p^(q-2)*q^(p-2) for p<q, a(2^2)=2, a(p^2)=p^(p-3)*2^(p-1) for p!=2.
MATHEMATICA
f[n_] := Block[{k = 1, m = If[ PrimeQ[n], n^(n-2), 1]}, While[ DivisorSigma[0, k*m*n] != n, k++ ]; k*m]; Table[f[n], {n, 29}] (* Robert G. Wilson v, Sep 29 2005 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Oct 18 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 21 2003
More terms from David Wasserman, Aug 19 2005
STATUS
approved