OFFSET
1,3
MATHEMATICA
Select[Range[0, 200], DigitCount[#, 10, 4] == DigitCount[#, 10, 9] &] (* Vincenzo Librandi, Oct 27 2016 *)
PROG
(Magma) [n: n in [0..120] | Multiplicity(S, 4) eq Multiplicity(S, 9) where S is {*d: d in Intseq(n)*}]; // Vincenzo Librandi, Oct 27 2016
(Python)
from itertools import count, islice
def A039145_gen(startvalue=0): # generator of terms >= startvalue
return filter(lambda k:(s:=str(k)).count('4')==s.count('9'), count(max(startvalue, 0)))
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved