A337816 Numbers that can be written as (m * sum of digits of m) for some m.

0, 1, 4, 9, 10, 16, 22, 25, 36, 40, 49, 52, 63, 64, 70, 81, 88, 90, 100, 112, 115, 124, 136, 144, 160, 162, 175, 190, 198, 202, 205, 208, 220, 238, 243, 250, 252, 280, 301, 306, 319, 324, 333, 352, 360, 364, 370, 400, 405, 412, 418, 424, 427, 448, 460, 468, 484, 486, 490

Offset

1,3

Comments

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

Links

Table of n, a(n) for n=1..59.

Example

10 = 10 * (1+0);
22 = 11 * (1+1).

Mathematica

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

Prog

(PARI) is(k)={if(k==0, return(1)); fordiv(k, d, if(d*sumdigits(d)==k, return(1))); 0} \\ Andrew Howroyd, Sep 23 2020

Crossrefs

Range of A057147 and of A117570.

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

Cf. A337817.

Some subsequences: A011557, A052268, A093141.

Sequence in context: A260963 A243188 A117570 * A272266 A155566 A305231

Adjacent sequences: A337813 A337814 A337815 * A337817 A337818 A337819

Keyword

nonn,base

Author

Bernard Schott, Sep 23 2020

Status

approved