This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A066640 #17 Nov 18 2024 11:02:27
%S A066640 1,3,5,7,9,11,13,15,17,19,31,33,35,37,39,51,53,55,57,59,71,73,77,79,
%T A066640 91,93,95,97,99,111,113,117,119,131,133,137,139,151,153,155,157,159,
%U A066640 171,173,177,179,191,193,197,199
%N A066640 Numbers such that all divisors have only odd digits.
%C A066640 Is this sequence infinite? - _Charles R Greathouse IV_, Sep 07 2012
%H A066640 Charles R Greathouse IV, <a href="/A066640/b066640.txt">Table of n, a(n) for n = 1..10000</a>
%e A066640 77 = 11 * 7 belongs to this sequence but 75 does not as 25 (with a 2) divides 75.
%t A066640 Select[Range[250], And@@OddQ/@Flatten[IntegerDigits/@Divisors[ # ]]&]
%o A066640 (PARI) f(n)=vecmin(Vec(Vecsmall(Str(n)))%2)
%o A066640 is(n)=fordiv(n,d,if(!f(d),return(0)));1 \\ _Charles R Greathouse IV_, Sep 07 2012
%o A066640 (Python)
%o A066640 from itertools import islice, count
%o A066640 from sympy import divisors
%o A066640 def A066640(): return filter(lambda n: all(set(str(m)) <= {'1','3','5','7','9'} for m in divisors(n,generator=True)), count(1,2))
%o A066640 A066640_list = list(islice(A066640(),20)) # _Chai Wah Wu_, Nov 22 2021
%Y A066640 Subsequence of A014261. A030096 is a subsequence.
%K A066640 nonn,base
%O A066640 1,2
%A A066640 _Amarnath Murthy_, Dec 28 2001
%E A066640 Corrected and extended by _Harvey P. Dale_, Jan 01 2002