OFFSET
1,1
EXAMPLE
14 and 15 are semiprimes. 14+1 = 15 is divisible by 1+4 = 5, hence 14 is in the sequence; 15+1 = 16 is not divisible by 1+5 = 6, hence 15 is not in the sequence. - Klaus Brockhaus, Sep 29 2008
MATHEMATICA
Select[Range[5000], Sum[FactorInteger[ # ][[i, 2]], {i, 1, Length[FactorInteger[ # ]]}] == 2 && Mod[ # + 1, Plus @@ IntegerDigits[ # ]] == 0 &] (* Stefan Steinerberger, Sep 29 2008 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Giovanni Teofilatto, Sep 27 2008
EXTENSIONS
Corrected and extended by Stefan Steinerberger and Klaus Brockhaus, Sep 29 2008
STATUS
approved