OFFSET
1,1
EXAMPLE
343 = 7^3; 3 digits in 343, 2 digits in 7^3, so 343 is economical.
MATHEMATICA
d[n_]:=IntegerDigits[n]; palQ[n_]:=Reverse[(x=d[n])]==x; ecQ[n_]:=Length[Flatten[d[{First/@(x=FactorInteger[n]), DeleteCases[Last/@x, 1]}]]] < Length[d[n]]; t={}; Do[If[palQ[n] && ecQ[n], AppendTo[t, n]], {n, 3860000}]; t (* Jayanta Basu, May 16 2013 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
a(11)-a(45) from Donovan Johnson, Nov 24 2010
STATUS
approved