A337816 - OEIS

%I #27 Sep 28 2020 02:36:28

%S 0,1,4,9,10,16,22,25,36,40,49,52,63,64,70,81,88,90,100,112,115,124,

%T 136,144,160,162,175,190,198,202,205,208,220,238,243,250,252,280,301,

%U 306,319,324,333,352,360,364,370,400,405,412,418,424,427,448,460,468,484,486,490

%N Numbers that can be written as (m * sum of digits of m) for some m.

%C If 3 divides a(n), then 9 divides a(n).

%e 10 = 10 * (1+0);

%e 22 = 11 * (1+1).

%t m = 500; Select[Union @ Table[k * Plus @@ IntegerDigits[k], {k, 0, m}], # <= m &] (* _Amiram Eldar_, Sep 23 2020 *)

%o (PARI) is(k)={if(k==0, return(1)); fordiv(k, d, if(d*sumdigits(d)==k, return(1))); 0} \\ _Andrew Howroyd_, Sep 23 2020

%Y Range of A057147 and of A117570.

%Y Similar sequences: A176995 (m + sum of digits of m), A336826 (m * product of digits of m), A337718 (m + product of digits of m).

%Y Cf. A337817.

%Y Some subsequences: A011557, A052268, A093141.

%K nonn,base

%O 1,3

%A _Bernard Schott_, Sep 23 2020