cp's OEIS Frontend

A276381 Numbers n such that there exist a number k with A007953(n) = A007953(k*n) and 1 < k < 10.

%I A276381 #30 Dec 29 2020 16:39:19
%S A276381 3,6,9,15,18,27,30,33,36,39,45,48,51,54,57,60,63,66,69,72,75,78,81,84,
%T A276381 87,90,93,96,99,105,108,117,126,129,135,138,144,147,150,153,156,159,
%U A276381 162,165,168,171,174,177,180,183,186,189,192,195,198,207,216,219,225,228,234,243
%N A276381 Numbers n such that there exist a number k with A007953(n) = A007953(k*n) and 1 < k < 10.
%C A276381 From _Robert Israel_, Dec 29 2020: (Start)
%C A276381 If n is a term, so are 10*n and (10^m+1)*n where 10^(m-1) > n.
%C A276381 All terms are divisible by 3. (End)
%H A276381 Robert Israel, <a href="/A276381/b276381.txt">Table of n, a(n) for n = 1..10000</a>
%e A276381 15 is a term because A007953(15) = A007953(4*15).
%p A276381 filter:= proc(n) local t,k;
%p A276381   t:= digsum(n);
%p A276381   for k from 2 to 9 do if digsum(k*n)=t then return true fi od;
%p A276381   false
%p A276381 end proc:
%p A276381 select(filter, [seq(i,i=3..1000,3)]); # _Robert Israel_, Dec 29 2020
%Y A276381 Cf. A007953, A070279, A259727, A259728, A259729.
%K A276381 nonn,easy,base
%O A276381 1,1
%A A276381 _Altug Alkan_, Sep 04 2016