OFFSET
1,1
COMMENTS
Resulting semiprimes in A112771.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = (A112771(n) - 1)/6.
MATHEMATICA
Select[Range[200], Plus@@Last/@FactorInteger[6#+1]==2&] (* Vincenzo Librandi, Sep 22 2012 *)
PROG
(Magma) IsSemiprime:=func<n | &+[k[2]: k in Factorization(n)] eq 2>; [n: n in [2..150] | IsSemiprime(6*n+1)]; // Vincenzo Librandi, Sep 22 2012
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post and Ray Chandler, Oct 15 2005
STATUS
approved