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

Author

Rémy Sigrist, Jan 31 2018

Keywords

• nonn
• base
• easy

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.

Examples

			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.
		

Crossrefs

Cf. A007953, A052268, A106039.

Programs

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)