%I #9 Dec 28 2023 18:56:00
%S 1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,21,22,23,24,25,26,27,28,
%T 29,31,32,33,34,35,36,37,38,39,41,42,43,44,45,46,47,48,49,51,52,53,54,
%U 55,56,57,58,59,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,81,82,83,84,85,86,87,88,89,91,92,93,94,95,96,97,98,99,111
%N Numbers n such that smallest digit of all divisors of n is 1.
%C Also numbers n such that smallest digit of concatenation of all divisors of n (A037278 or A176558) is 1.
%C Sequence is not the same as A052382, first deviation is at a(175): A052382(175) = 214, a(175) = 215.
%C Sequence is not the same as A067251, first deviation is at a(91): A067251 (91) = 101, a(91) = 111.
%C Complement of A209932.
%e Number 24 is in sequence because smallest digit of all divisors of 24 (1, 2, 4, 8, 3, 6, 12, 24) is 1.
%p isA209931 := proc(n)
%p digsdiv := {} ;
%p for d in numtheory[divisors](n) do
%p dgs := convert(convert(d,base,10),set) ;
%p digsdiv := digsdiv union dgs ;
%p end do:
%p if 0 in digsdiv then
%p false;
%p else
%p true ;
%p end if;
%p end proc:
%p A209931 := proc(n)
%p option remember;
%p if n =1 then
%p 1;
%p else
%p for a from procname(n-1)+1 do
%p if isA209931(a) then
%p return a;
%p end if;
%p end do;
%p end if;
%p end proc:
%p seq(A209931(n),n=1..120) ;# _R. J. Mathar_, Dec 28 2023
%Y Cf. A052382, A067251, A209929 (smallest digit of all divisors of n).
%K nonn,base
%O 1,2
%A _Jaroslav Krizek_, Mar 20 2012
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