A098949 - OEIS

%I #22 Sep 29 2021 07:09:44

%S 9,29,49,69,89,90,92,94,96,98,99,209,229,249,269,289,290,292,294,296,

%T 298,299,409,429,449,469,489,490,492,494,496,498,499,609,629,649,669,

%U 689,690,692,694,696,698,699,809,829,849,869,889,890,892,894,896,898

%N Numbers where 9 is the only odd decimal digit.

%C This is a regular language in base 10. - _Charles R Greathouse IV_, Oct 05 2011

%C The number of terms of this sequence that are smaller than 10^n is n*5^(n-1). - _Stefan Steinerberger_, Jun 06 2006

%C Any number of 9s is permitted. - _Harvey P. Dale_, May 07 2019

%H Harvey P. Dale, <a href="/A098949/b098949.txt">Table of n, a(n) for n = 1..2000</a>

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>

%t Select[Range[1000], DigitCount[ # ][[1]] == 0 && DigitCount[ # ][[3]] == 0 && DigitCount[ # ][[5]] == 0 && DigitCount[ # ][[7]] == 0 && DigitCount[ # ][[9]] >0 &] (* _Stefan Steinerberger_, Jun 06 2006; corrected by _Harvey P. Dale_, May 07 2019 *)

%t Select[Range[1000],Union[Select[IntegerDigits[#],OddQ]]=={9}&] (* _Harvey P. Dale_, May 07 2019 *)

%o (Perl) for (0..1000) {

%o     print "$_, " if (/^[024689]*9[024689]*$/)

%o } # _Charles R Greathouse IV_, Oct 05 2011

%o (Python)

%o def ok(n): return set(str(n)) & set("13579") == set("9")

%o print(list(filter(ok, range(899)))) # _Michael S. Branicky_, Sep 29 2021

%K base,easy,nonn

%O 1,1

%A _Eric Angelini_, Oct 21 2004

%E More terms from _Stefan Steinerberger_, Jun 06 2006