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A295430 a(n) is the least nontrivial multiple of n that begins with 3.

%I A295430 #16 Feb 20 2018 22:51:21
%S A295430 3,30,30,32,30,30,35,32,36,30,33,36,39,308,30,32,34,36,38,300,315,308,
%T A295430 322,312,300,312,324,308,319,300,310,320,330,306,315,324,333,304,312,
%U A295430 320,328,336,301,308,315,322,329,336,343,300,306,312,318,324,330,336,342,348,354,300,305,310,315
%N A295430 a(n) is the least nontrivial multiple of n that begins with 3.
%H A295430 Robert Israel, <a href="/A295430/b295430.txt">Table of n, a(n) for n = 1..10000</a>
%p A295430 f:= proc(n) local m,k;
%p A295430   for m from 0 do
%p A295430     k := max(2, ceil(3*10^m/n));
%p A295430     if k*n < 4*10^m then return k*n end if
%p A295430   end do
%p A295430 end proc:
%p A295430 seq(f(i),i=1..100);
%o A295430 (PARI) a(n) = {my(k=2); while(digits(k*n)[1] != 3, k++); k*n;} \\ _Michel Marcus_, Feb 13 2018
%o A295430 (Python)
%o A295430 def A295430(n):
%o A295430     m = 2*n
%o A295430     while True:
%o A295430         if str(m)[0] == '3':
%o A295430             return m
%o A295430         m += n # _Chai Wah Wu_, Feb 13 2018
%Y A295430 Cf. A082792.
%K A295430 nonn
%O A295430 1,1
%A A295430 _Robert Israel_, Feb 12 2018