A276381 - OEIS

A276381

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

3, 6, 9, 15, 18, 27, 30, 33, 36, 39, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 105, 108, 117, 126, 129, 135, 138, 144, 147, 150, 153, 156, 159, 162, 165, 168, 171, 174, 177, 180, 183, 186, 189, 192, 195, 198, 207, 216, 219, 225, 228, 234, 243

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OFFSET

1,1

COMMENTS

From Robert Israel, Dec 29 2020: (Start)

If n is a term, so are 10*n and (10^m+1)*n where 10^(m-1) > n.

All terms are divisible by 3. (End)

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

15 is a term because A007953(15) = A007953(4*15).

MAPLE

filter:= proc(n) local t, k;

t:= digsum(n);

for k from 2 to 9 do if digsum(k*n)=t then return true fi od;

false

end proc:

select(filter, [seq(i, i=3..1000, 3)]); # Robert Israel, Dec 29 2020

CROSSREFS

Cf. A007953, A070279, A259727, A259728, A259729.

Sequence in context: A179893 A274191 A133331 * A259728 A000741 A133205

Adjacent sequences: A276378 A276379 A276380 * A276382 A276383 A276384

KEYWORD

nonn,easy,base

AUTHOR

Altug Alkan, Sep 04 2016

STATUS

approved