OFFSET
1,1
MATHEMATICA
Select[Range@4000, (s=#; Differences[Count[IntegerDigits[s, 4], #]&/@{0, 3}]=={4})&] (* Giorgos Kalogeropoulos, Jul 04 2021 *)
Select[Range[3600], DigitCount[#, 4, 0]==DigitCount[#, 4, 3]-4&] (* Harvey P. Dale, Oct 01 2021 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved