OFFSET
1,1
MATHEMATICA
SequencePosition[Table[If[SequenceCount[IntegerDigits[n], {5, 7}]>0 || SequenceCount[ IntegerDigits[n], {7, 5}]>0 , 1, 0], {n, 2100}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 04 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved