A298984 Numbers k such that floor((10^p) / k) has digital sum k for some integer p.

1, 3, 7, 8, 9, 13, 14, 22, 30, 33, 34, 43, 49, 51, 55, 56, 62, 66, 73, 76, 83, 90, 91, 92, 94, 95, 96, 98, 99, 103, 109, 113, 127, 129, 130, 132, 133, 137, 139, 141, 150, 154, 159, 169, 170, 174, 175, 177, 179, 180, 181, 185, 186, 192, 194, 202, 208, 211, 215

Offset

1,2

Comments

This sequence has similarities with A106039: here some partial sum of digits of 1/k equals k, there some partial (cyclical) sum of digits of k equals k.

A052268 is a subsequence.

Links

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

Example

floor(1000 / 7) = 142 and 1 + 4 + 2 = 7, hence 7 belongs to this sequence.
floor(1 / 5) = 0 and floor ((10^p) / 5) = 2 for any p > 0, hence 5 does not belong to this sequence.

Prog

(PARI) is(n) = my (r=1/n, s=0); while (r, s+=floor(r); if (s==n, return (1), s>n, return (0); r = frac(r)*10); return (0)

Crossrefs

Cf. A007953, A052268, A106039.

Sequence in context: A286395 A112680 A096079 * A094551 A342006 A239937

Adjacent sequences: A298981 A298982 A298983 * A298985 A298986 A298987

Keyword

nonn,base,easy

Author

Rémy Sigrist, Jan 31 2018

Status

approved