OFFSET
1,1
EXAMPLE
First semiprime is 4; 4 is 2*2 -> 22.
Second semiprime is 6; 6 is 2*3 -> 23.
...
Eighth semiprime is 22; 22 is 11*2 -> 112 (and not 211).
MATHEMATICA
f[n_]:=Module[{ids=IntegerDigits/@Transpose[FactorInteger[n]][[1]], a, b}, a =FromDigits[ Join[ First[ids], Last[ids]]]; b=FromDigits[ Join[ Last[ids], First[ids]]]; Min[a, b]]; f/@Select[Range[200], PrimeOmega[#] ==2&] (* Harvey P. Dale, Jun 20 2011 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini, May 09 2005
EXTENSIONS
More terms from Harvey P. Dale, Jun 20 2011
STATUS
approved