OFFSET
1,1
EXAMPLE
a(4)=15 because k=2 and prime factors are 3 and 5; 15 is odd and n-2=13, prime.
MATHEMATICA
Contribution from Farideh Firoozbakht, Aug 13 2009: (Start)
a[n_]:=(c=Product[Prime[k], {k, n}]; For[m=1, !(!PrimeQ[c*m]&&PrimeQ[c*m-1]
&&Length[FactorInteger[c*m]]==n), m++ ]; c*m); b[n_]:=(c=Product[Prime[k],
{k, 2, n+1}]; For[m=1, !(!PrimeQ[c(2m-1)]&&PrimeQ[c(2m-1)-2]&&Length[FactorInteger
[c(2*m-1)]]==n), m++ ]; c(2m-1)); Take[Union[Table[a[k], {k, 24}], Table[b[k],
{k, 24}]], 24] (End)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Enoch Haga, Dec 25 2007
EXTENSIONS
Edited, corrected and extended by Farideh Firoozbakht, Aug 13 2009
STATUS
approved