OFFSET
1,2
EXAMPLE
The terms a(5) = 11, a(6) = 3 are allowed since in both terms altogether the digit 1 appears twice. On the contrary, a(n-1) = 11, a(n) = 12 are not allowed since the digit 1 appears three times. Also a(n-1) = 11, a(n) = 22 are not allowed since two digits (not one) appear twice.
MATHEMATICA
L = {1}; While[Length[L] < 100, k=2; While[ MemberQ[L, k] || (d = Plus @@ DigitCount[{k, L[[-1]]}]; ! SubsetQ[{0, 1, 2}, d] || Count[d, 2] != 1), k++]; AppendTo[L, k]]; L (* Giovanni Resta, May 22 2017 *)
CROSSREFS
KEYWORD
nonn,fini,base
AUTHOR
Enrique Navarrete, May 15 2017
EXTENSIONS
Data corrected by Giovanni Resta, May 22 2017
STATUS
approved