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%I #21 Sep 08 2022 08:46:13
%S 0,9,18,27,36,45,54,72,81,90,99,108,117,135,144,171,180,189,198,207,
%T 234,270,279,288,297,342,351,360,396,405,414,441,450,459,486,495,504,
%U 540,549,558,576,585,594,639,648,657,693,702,711,720,729,756,765,783,792
%N Sum of digits of a(n) equals the sum of digits of 3*a(n).
%C A007953(a(n)) = A007953(3*a(n)).
%C 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.
%e 99 belongs to the sequence, because A007953(99) = 18 = A007953(297) = A007953(3*99).
%t Select[Range[0, 800], Total@ IntegerDigits@ # == Total@ IntegerDigits[3 #] &] (* _Michael De Vlieger_, Aug 05 2015 *)
%o (PARI) select(x->sumdigits(x)==sumdigits(3*x),vector(10^4,n,n)) \\ _Joerg Arndt_, Jul 04 2015
%o (Magma) [n: n in [0..800] | &+Intseq(n) eq &+Intseq(3*n)]; // _Vincenzo Librandi_, Aug 05 2015
%Y Cf. A007953, A070279, A259728, A259729.
%K nonn,easy,base
%O 1,2
%A _Christina Steffan_, Jul 04 2015
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