OFFSET
0,1
COMMENTS
Impossible numbers below 10000 are 1000, 10000, and numbers == 10 mod(100), == 89 mod(100), == 100 (mod 1000), or == 899 (1000).
MATHEMATICA
f = Compile[{{n, _Integer}}, Module[{k = 1, id1 = DeleteCases[IntegerDigits[n], 0], id2 = DeleteCases[IntegerDigits[2 n], 0]}, While[k < 10001 && Intersection[id1, id2] != {}, id1 = id2; k++; id2 = DeleteCases[Union[IntegerDigits[(k + 1) n]], 0]]; If[k == 10001, 0, k]]]; t[_] := -1; k = 1; While[k < 33001, a = f@k; If[t[a] == -1, t[a] = k; Print[{a, k}]]; k++]; (t@# & /@ Range[0, 100]) /. {-1 -> 0}
CROSSREFS
KEYWORD
nonn,base
AUTHOR
David Radcliffe, Daniel Griller, and Robert G. Wilson v, Jul 16 2019
STATUS
approved