OFFSET
1,1
COMMENTS
EXAMPLE
63540 = 1440 * 411 = 2520 * 252 = 4410 * 144.
MATHEMATICA
f[n_] := (m = ToExpression[StringReverse[ToString[n]]]; If[n > m, n*m, 0]); a = Sort[ Table[ f[n], {n, 0, 10^6}]]; While[ a[[1]] == 0, a = Drop[a, 1]]; a[[ Select[ Range[ Length[a]] - 2, a[[ # ]] == a[[ # + 2 ]] & ]]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jan 08 2002
EXTENSIONS
Definition clarified by M. F. Hasler, Feb 14 2012
Definition corrected by N. J. A. Sloane, Aug 01 2019
STATUS
approved