A259729 -id:A259729 - cp's OEIS frontend

A259727 Sum of digits of a(n) equals the sum of digits of 3*a(n).

0, 9, 18, 27, 36, 45, 54, 72, 81, 90, 99, 108, 117, 135, 144, 171, 180, 189, 198, 207, 234, 270, 279, 288, 297, 342, 351, 360, 396, 405, 414, 441, 450, 459, 486, 495, 504, 540, 549, 558, 576, 585, 594, 639, 648, 657, 693, 702, 711, 720, 729, 756, 765, 783, 792

Offset: 1

Christina Steffan, Jul 04 2015

A007953(a(n)) = A007953(3*a(n)).

a(n) is a multiple of 9, but not all multiples of 9 belong to the sequence: e.g., 63 = 7*9: A007953(63) = 6 + 3 = 9, but A007953(3*63) = A007953(189) = 1 + 8 + 9 = 18.

			99 belongs to the sequence, because A007953(99) = 18 = A007953(297) = A007953(3*99).

Cf. A007953, A070279, A259728, A259729.

[n: n in [0..800] | &+Intseq(n) eq &+Intseq(3*n)]; // Vincenzo Librandi, Aug 05 2015

Select[Range[0, 800], Total@ IntegerDigits@ # == Total@ IntegerDigits[3 #] &] (* Michael De Vlieger, Aug 05 2015 *)

select(x->sumdigits(x)==sumdigits(3*x),vector(10^4,n,n)) \\ Joerg Arndt, Jul 04 2015

A259728 Sum of digits of a(n) equals the sum of digits of 4*a(n).

Original entry on oeis.org

0, 3, 6, 9, 15, 18, 27, 30, 33, 36, 39, 45, 48, 51, 54, 57, 60, 63, 66, 69, 81, 84, 87, 90, 93, 96, 99, 105, 108, 126, 129, 135, 138, 150, 153, 156, 159, 165, 168, 177, 180, 183, 186, 189, 195, 198, 225, 228, 252, 261, 264, 267, 270, 273, 282, 291, 294, 297

Offset: 1

Christina Steffan, Jul 05 2015

A007953(a(n)) = A007953(4*a(n)).

a(n) is a multiple of 3, but not all multiples of 3 belong to the sequence: e.g., 12 = 4*3: A007953(12) = 1 + 2 = 3, but A007953(4*12) = A007953(48) = 4 + 8 = 12.

			15 belongs to the sequence, because A007953(15) = 6 = A007953(60) = A007953(4*15).

Cf. A007953, A070279, A259727, A259729.

[n: n in [0..400] | &+Intseq(n) eq &+Intseq(4*n)]; // Vincenzo Librandi, Aug 05 2015

More terms from Vincenzo Librandi, Aug 05 2015

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

Original entry on oeis.org

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

Offset: 1

Altug Alkan, Sep 04 2016

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)

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

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

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

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

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A259727 Sum of digits of a(n) equals the sum of digits of 3*a(n).

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A259728 Sum of digits of a(n) equals the sum of digits of 4*a(n).

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

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