OFFSET
1,2
EXAMPLE
n=5: a(5)=25 because tau(25)+5 = 3+5 = 8 = tau(25+5) = tau(30).
MATHEMATICA
ds[x_, de_] :=DivisorSigma[0, x+de]-DivisorSigma[0, x]-de; a[n_] :=Block[{m=1, s=ds[m, n]}, While[(s!=0||PrimeQ[m])&&!Greater[m, 10000000], m++ ]; m];
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 02 2004
STATUS
approved