OFFSET
1,1
COMMENTS
EXAMPLE
a(1) = 4 because 4 (base 6) = 4 and 4 (base 10) = 2 * 2, a semiprime (A001358).
a(2) = 6 because 6 (base 6) = 10 and 10 (base 10) = 2 * 5.
a(3) = 10 because 10 (base 6) = 14 and 14 (base 10) = 2 * 7.
a(4) = 11 because 11 (base 6) = 15 and 15 (base 10) = 3 * 5.
a(5) = 13 because 13 (base 6) = 21 and 21 (base 10) = 3 * 7.
MATHEMATICA
Select[Range[191], Plus @@ Last /@ FactorInteger[FromDigits[IntegerDigits[ #, 6]]] == 2 &] (* Ray Chandler, Aug 05 2005 *)
Select[Range[200], PrimeOmega[FromDigits[IntegerDigits[#, 6]]]==2&] (* Harvey P. Dale, Oct 02 2011 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Jonathan Vos Post, Jul 30 2005
EXTENSIONS
Corrected and extended by Ray Chandler, Aug 05 2005
STATUS
approved