OFFSET
1,1
MATHEMATICA
f2[upto_]:=Module[{maxno=Floor[(3+Sqrt[12*upto-3])/6]}, Select[Union[Last[#]-First[ #]& /@Subsets[Range[maxno]^3, {2}]], #<=upto&&Last[IntegerDigits[#]]==1&]]; f[13000] (* Harvey P. Dale, Mar 03 2011 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
Corrected and extended by Ray Chandler, Nov 29 2008
STATUS
approved